From 7ed774089e51341c6bc941f4f8899eb8450098d1 Mon Sep 17 00:00:00 2001
From: allexanderbergmns <socials@libregrad.pp.ua>
Date: Tue, 25 Aug 2026 16:20:11 +0200
Subject: [PATCH] More buildins and vscode exstention <CO-AUthored, ai>

---
 .github/workflows/ci.yml                    |  13 +
 .github/workflows/release.yml               |  22 +-
 README.MD                                   |  49 +-
 compiler/check.v                            |  11 +-
 compiler/codegen.v                          | 264 +++++++++-
 compiler/lexer.v                            |  20 +
 compiler/opcodes.v                          |  21 +
 examples/stdlib.vr                          | 102 ++++
 examples/tests.vr                           |  75 ++-
 extension/client/extension.js               |  53 ++
 extension/language-configuration.json       |  23 +
 extension/package.json                      |  61 +++
 extension/syntaxes/vuurraaf.tmLanguage.json | 160 ++++++
 lib/crypto.vr                               |  23 +
 lib/csv.vr                                  |  13 +
 lib/http.vr                                 |  23 +
 lib/os.vr                                   |  20 +
 lib/regex.vr                                |  30 ++
 lib/time.vr                                 |  23 +
 lsp.v                                       | 537 ++++++++++++++++++++
 main.v                                      | 112 +++-
 vm/gc.v                                     |  10 +
 vm/json.v                                   |   4 +-
 vm/native.v                                 | 213 +++++++-
 vm/opcodes.v                                |  21 +
 vm/types.v                                  |  49 +-
 vm/vm.v                                     | 250 ++++++---
 27 files changed, 2080 insertions(+), 122 deletions(-)
 create mode 100644 examples/stdlib.vr
 create mode 100644 extension/client/extension.js
 create mode 100644 extension/language-configuration.json
 create mode 100644 extension/package.json
 create mode 100644 extension/syntaxes/vuurraaf.tmLanguage.json
 create mode 100644 lib/crypto.vr
 create mode 100644 lib/csv.vr
 create mode 100644 lib/regex.vr
 create mode 100644 lsp.v

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c18648a..858a650 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -64,3 +64,16 @@ jobs:
           grep -n 'fn test_failing' examples/tests.vr || true
           sed '/fn test_failing/,/^}/d' examples/tests.vr > /tmp/ci_tests.vr
           ./bin/vr test /tmp/ci_tests.vr
+
+      - name: Run stdlib test suite
+        run: |
+          ./bin/vr test examples/stdlib.vr
+
+      - name: LSP smoke test
+        run: |
+          BODY='{"jsonrpc":"2.0","id":1,"method":"initialize","params":{}}'
+          printf 'Content-Length: %d\r\n\r\n%s' "${#BODY}" "$BODY" | ./bin/vr lsp | grep -q '"id":1' && echo "LSP responded"
+
+      - name: Watch-mode and directory-test smoke
+        run: |
+          ./bin/vr test examples | grep -q 'passed'
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index c6793e5..64af92f 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -19,6 +19,9 @@ jobs:
           - os: macos-latest
             artifact: vr-macos-arm64
             binary: vr
+          - os: windows-latest
+            artifact: vr-windows-amd64.exe
+            binary: vr.exe
 
     runs-on: ${{ matrix.os }}
 
@@ -26,17 +29,30 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
 
-      - name: Install V
+      - name: Install V (unix)
+        if: runner.os != 'Windows'
+        shell: bash
         run: |
           git clone --depth 1 https://github.com/vlang/v /tmp/v
           cd /tmp/v && make
           sudo ln -sf /tmp/v/v /usr/local/bin/v
           v version
 
+      - name: Install V (windows)
+        if: runner.os == 'Windows'
+        shell: bash
+        run: |
+          curl -L -o v_windows.zip https://github.com/vlang/v/releases/latest/download/v_windows.zip
+          unzip -o v_windows.zip -d /tmp/vwin
+          echo "/tmp/vwin/v" >> "$GITHUB_PATH"
+          v version
+
       - name: Build toolchain
+        shell: bash
         run: v -o ${{ matrix.binary }} .
 
       - name: Smoke test
+        shell: bash
         run: ./${{ matrix.binary }} run examples/hello.vr
 
       - name: Upload artifact
@@ -57,7 +73,7 @@ jobs:
       - name: Verify tag matches v.mod version
         run: |
           TAG="${GITHUB_REF#refs/tags/v}"
-          MOD_VERSION=$(grep -oP "version: '\K[^"]+" v.mod)
+          MOD_VERSION=$(grep -oP "version: '\\K[^\"]+" v.mod)
           if [ "$TAG" != "$MOD_VERSION" ]; then
             echo "::error::Tag version (v${TAG}) does not match v.mod version (${MOD_VERSION})"
             exit 1
@@ -74,7 +90,7 @@ jobs:
           mkdir -p release
           for dir in artifacts/*/; do
             name=$(basename "$dir")
-            cp "$dir"/vr release/"$name"
+            cp "$dir"/* release/"$name"
             chmod +x release/"$name"
           done
           ls -lh release/
diff --git a/README.MD b/README.MD
index 30aeae4..ca7beea 100644
--- a/README.MD
+++ b/README.MD
@@ -41,6 +41,7 @@ vr up                                       rebuild bin/vr
 vr symlink                                  link bin/vr into your PATH
 vr config [set <key> <value>]               toolchain config (outdir, verbose)
 vr repl                                     interactive session
+vr lsp                                      language server (JSON-RPC over stdio)
 vr fmt [-w] <file.vr>                       format source (keeps comments)
 vr init [name]                              scaffold a project (vr.mod + main.vr)
 vr get <owner/repo | git-url | ./path>      fetch a package into vendor/
@@ -53,6 +54,9 @@ vr info | loader | alloc | version | help
 ./bin/vr repl          # try expressions and functions interactively
 ./bin/vr fmt -w f.vr   # normalize a file's indentation/spacing in place
 ./bin/vr init myproj   # start a project; vr get owner/repo fetches packages
+./bin/vr run -w f.vr   # watch f.vr and rerun on every save
+./bin/vr test examples # run every test_* fn in every .vr file under examples/
+./bin/vr lsp           # language server for editors (diagnostics, go-to-def)
 ```
 
 Quick start:
@@ -165,12 +169,17 @@ Module functions are namespaced: `os.exists()`, `json.encode()`, ...
 
 | module | functions |
 | --- | --- |
-| `os` | filesystem + process: `exists`, `is_dir`, `is_file`, `mkdir`, `remove`, `copy`, `list_dir`, `glob`, `join`, `base`, `dir`, `read_lines`, `write_lines`, `cwd`, `env`, `exec` |
+| `os` | filesystem + process: `exists`, `is_dir`, `is_file`, `mkdir`, `remove`, `copy`, `list_dir`, `glob`, `join`, `base`, `dir`, `read_lines`, `write_lines`, `cwd`, `env`, `exec`, `exec_full` (`{code, stdout, stderr}`), `ext`, `abs`, `rel` |
 | `json` | `encode`, `decode`, `pretty` — objects become structs, integral numbers decode as ints, `null` ⇄ `none` |
 | `strings` | `length`, `lines`, `split`, `join`, `replace`, `contains`, `starts_with`, `ends_with`, `upper`, `lower`, `trim`, `pad`, `pad_left`, `repeat`, `format`, `capitalize` |
 | `math` | `abs`, `min`, `max`, `floor`, `ceil`, `round`, `sqrt`, `pow`, `clamp`, `sign`, `pi` |
-| `http` | `get(url)`, `post(url, data)`, `get_text(url)` — return `{status, body}`; network failures throw (catchable), HTTP errors (404) are normal responses |
-| `time` | `now()` (epoch s), `ms()` (epoch ms), `format(t, "YYYY-MM-DD HH:mm:ss")`, `date(t)`, `clock(t)`, `parse("2026-08-25 13:36:45")` — Moment-style tokens |
+| `http` | `get(url)`, `post(url, data)`, `get_text(url)`, `request(method, url, data, headers, timeout_ms)`, `get_with_headers`, `post_with_headers`, `get_timeout`, `post_timeout` — return `{status, body}`; network failures throw (catchable), HTTP errors (404) are normal responses |
+| `time` | `now()` (epoch s), `ms()` (epoch ms), `format(t, "YYYY-MM-DD HH:mm:ss")`, `date(t)`, `clock(t)`, `parse("2026-08-25 13:36:45")`, `add_days/add_hours/add_minutes/add_seconds`, `weekday(t)` — Moment-style tokens |
+| `regex` | `is_match(pattern, s)`, `find_all(pattern, s)`, `replace(pattern, s, repl)`, `split(pattern, s)` — RE2 syntax; use raw strings `r"\d+"` for patterns |
+| `crypto` | `sha256(s)`, `md5(s)`, `base64_encode(s)`, `base64_decode(s)` |
+| `csv` | `parse(s)` — returns an array of rows (arrays of cell strings) |
+
+Examples: `examples/imports.vr`, `examples/http.vr`, `examples/time.vr`, `examples/stdlib.vr` (tests for the regex/crypto/csv/os/time additions).
 
 Examples: `examples/imports.vr`, `examples/http.vr`, `examples/time.vr`.
 
@@ -257,7 +266,12 @@ fn main() {
 - functions: `fn name(a, b) { ... }` with `return expr`; default parameter
   values `fn f(a, b = 10)`, variadic params `fn f(nums...)`, destructuring
   `let { a, b } = rec` and `let [x, y] = arr`, and anonymous closures
-  `let f = fn(x) { return x * 2 }` stored in variables and arrays
+  `let f = fn(x) { return x * 2 }` stored in variables and arrays; a closure
+  **captures the enclosing locals it references by value** (nested closures
+  included), so `let n = 1; let bump = fn() { n = n + 1; return n }` works —
+  writes hit the closure's own copy, the outer variable is untouched
+- raw strings: `r"..."` passes text through verbatim (no escape processing),
+  ideal for regex patterns like `r"\d+"`
 - generics: `fn first[T](arr) { return arr[0] }` with checked call sites
   `first[int](arr)` — the VM is dynamically typed, so type parameters erase
   to a single function but arity and duplicates are validated
@@ -269,6 +283,9 @@ fn main() {
   and slice by character (runes), and methods like `s.to_upper()`,
   `s.contains(x)`, `s.split(d)`, `s.index_of(x)`, `s.to_int()`, `s.len()`
   work on any string-valued expression
+- maps: structs serve as string-keyed maps with **hash-indexed O(1)** access;
+  keys may be computed expressions (`m[key_var] = v`, `m[key_var]`), not just
+  literals; `has(m, k)`, `delete(m, k)`, `keys(m)`, `len(m)` all work
 - arrays: `[e1, e2, ...]`, indexing `a[i]` (read and write), `len(a)`,
   `push/insert/remove/pop/sort/reverse/clone/index_of/join`; array literals
   may nest
@@ -355,7 +372,7 @@ field name as a string first, exactly like the compiler does).
 | `compiler/`  | lexer, parser, type checker, bytecode codegen (VROBJ)      |
 | `assembler/` | `.vasm` -> VROBJ                                            |
 | `linker/`    | resolves relocations, rebases strings, emits VRBIN          |
-| `vm/`        | stack VM: tagged values, call frames, string/array heaps    |
+| `vm/`        | stack VM: tagged values, call frames, string/array heaps, hash-indexed structs, GC-traced closure captures |
 | `obj/`       | VROBJ/VRBIN binary formats                                  |
 | `bin/`       | small standalone tools: `tl_alloc.v`, `tl_loader.v`         |
 
@@ -364,13 +381,31 @@ ints, string/array/struct/float/closure handles — so no integer ever
 collides with a heap handle. A mark-and-sweep garbage collector runs between
 opcodes when the heap grows past a threshold, tracing the stack (which holds
 every frame's locals) and compacting the pools; string constants baked into
-bytecode are never collected. Bytecode carries a line table, so runtime
-errors report the source line. A conservative compile-time type checker
+bytecode are never collected. Structs carry a hash index, so map-style field
+access is O(1); closure captures live inside the closure and are traced and
+remapped by the GC like any other heap value. Bytecode carries a line table,
+so runtime errors report the source line **and a full call-stack trace**
+(`fn` → line for every frame). A conservative compile-time type checker
 (`compiler/check.v`) rejects provably wrong programs (unknown variables,
 field access on numbers, arithmetic on strings, wrong arity) while leaving
 dynamic programs alone. `vr debug` prints every instruction with the stack
 contents (arrays rendered as `[1, 2, ...]`).
 
+## Editor support
+
+`vr lsp` speaks LSP over stdio, so any LSP-capable editor gets diagnostics
+(the compiler's errors, positioned at the right line), go-to-definition
+(functions, structs, enums, constants, locals, and stdlib module functions),
+and hover (symbol kind + line). The `extension/` folder contains a VS Code
+client (`code --install-extension extension/` after `npm install` in
+`extension/`) with syntax highlighting, or point any other LSP client at
+`vr lsp`.
+
+## Releases
+
+Tagging `vX.Y.Z` (matching `v.mod`) builds `vr` for Linux, macOS and
+Windows and attaches them to a GitHub Release.
+
 ## Repository layout
 
 ```
diff --git a/compiler/check.v b/compiler/check.v
index d93fde4..7c30b32 100644
--- a/compiler/check.v
+++ b/compiler/check.v
@@ -613,7 +613,16 @@ fn builtin_result_type(name string) TypeInfo {
 		'http_get', 'http_post' { TypeInfo{ kind: .struct_t } }
 		// date/time
 		'now', 'time_ms', 'parse_time' { TypeInfo{ kind: .int_t } }
-		'format_time' { TypeInfo{ kind: .string_t } }
+		'format_time', 'weekday' { TypeInfo{ kind: .string_t } }
+		// regex
+		'regex_match' { TypeInfo{ kind: .int_t } }
+		'regex_find_all', 'regex_split', 'csv_parse' { TypeInfo{ kind: .array_t } }
+		'regex_replace' { TypeInfo{ kind: .string_t } }
+		// crypto/encoding
+		'base64_encode', 'base64_decode', 'sha256', 'md5' { TypeInfo{ kind: .string_t } }
+		// extended HTTP + path/process helpers
+		'http_req', 'exec_full' { TypeInfo{ kind: .struct_t } }
+		'path_ext', 'path_abs', 'path_rel' { TypeInfo{ kind: .string_t } }
 		else { TypeInfo{ kind: .unknown } }
 	}
 }
diff --git a/compiler/codegen.v b/compiler/codegen.v
index 8d95874..9df1494 100644
--- a/compiler/codegen.v
+++ b/compiler/codegen.v
@@ -44,6 +44,7 @@ mut:
 	enter_off u32
 	next_lbl  int
 	modules   map[string]bool // imported module names (bare `import os`)
+	captures  []string        // enclosing locals captured by the closure being compiled
 }
 
 fn gen(prog Program) !obj.Obj {
@@ -121,6 +122,7 @@ fn gen(prog Program) !obj.Obj {
 		}
 	}
 	for fd in prog.fns {
+		g.captures = []string{} // top-level functions capture nothing
 		g.gen_fn(fd)!
 	}
 	return obj.Obj{
@@ -142,9 +144,16 @@ fn (mut g Gen) gen_fn(fd FnDecl) ! {
 	g.locals.clear()
 	g.types.clear()
 	g.local_cnt = 0
-	g.argc = fd.params.len + if fd.recv_type.len > 0 { 1 } else { 0 }
+	// closure captures occupy the leading local slots (filled by the caller's
+	// op_call_closure), then the receiver (methods), then the parameters
+	g.argc = fd.params.len + g.captures.len + if fd.recv_type.len > 0 { 1 } else { 0 }
 	mut next := 0
-	if fd.recv_type.len > 0 {
+	if g.captures.len > 0 {
+		for i, c in g.captures {
+			g.locals[c] = i
+		}
+		next = g.captures.len
+	} else if fd.recv_type.len > 0 {
 		g.locals[fd.recv_name] = 0
 		g.types[fd.recv_name] = fd.recv_type
 		next = 1
@@ -711,6 +720,9 @@ fn (mut g Gen) gen_expr(e Expr) ! {
 		.anon_fn {
 			g.lam_counter++
 			name := '__lam_${g.lam_counter}'
+			// find the enclosing locals the body references (its free
+			// variables); they become this closure's captures
+			caps := g.scan_captures(e.fn_body, e.fparams)
 			// jump over the lambda body so callers don't fall through
 			g.code << op_jmp
 			g.code << obj.encode_i64(0)
@@ -735,8 +747,10 @@ fn (mut g Gen) gen_expr(e Expr) ! {
 			saved_local_cnt := g.local_cnt
 			saved_enter_off := g.enter_off
 			saved_argc := g.argc
+			saved_captures := g.captures
 			g.labels.clear()
 			g.fixups = []Fixup{}
+			g.captures = caps
 			g.gen_fn(fd)!
 			// Restore the enclosing state.
 			g.fixups = saved_fixups
@@ -746,12 +760,18 @@ fn (mut g Gen) gen_expr(e Expr) ! {
 			g.local_cnt = saved_local_cnt
 			g.enter_off = saved_enter_off
 			g.argc = saved_argc
+			g.captures = saved_captures
 			// Patch the skip jump to land at the closure opcode we emit next
 			// (PC-relative, like all other jump targets).
 			obj.patch_i64(mut g.code, skip_fix_off, i64(g.code.len - (int(skip_fix_off) + 8)))
+			// capture the enclosing locals' current values (capture by value)
+			for cname in caps {
+				g.emit_load(g.locals[cname])
+			}
 			g.code << op_closure
 			g.code << obj.encode_i64(0)
 			g.relocs << obj.Reloc{ offset: u32(g.code.len) - 8, name: name, kind: 0 }
+			g.code << obj.encode_i64(i64(caps.len))
 		}
 		.bool_lit {
 			g.code << op_push_i
@@ -982,6 +1002,24 @@ fn builtin_spec(name string) (int, int) {
 		'time_ms' { native_time_ms, 0 }
 		'format_time' { native_format_time, 2 }
 		'parse_time' { native_parse_time, 1 }
+		'weekday' { native_weekday, 1 }
+		// regex
+		'regex_match' { native_regex_match, 2 }
+		'regex_find_all' { native_regex_find_all, 2 }
+		'regex_replace' { native_regex_replace, 3 }
+		'regex_split' { native_regex_split, 2 }
+		// crypto/encoding
+		'base64_encode' { native_base64_encode, 1 }
+		'base64_decode' { native_base64_decode, 1 }
+		'sha256' { native_sha256, 1 }
+		'md5' { native_md5, 1 }
+		'csv_parse' { native_csv_parse, 1 }
+		// extended HTTP + path/process helpers
+		'http_req' { native_http_req, 5 }
+		'path_ext' { native_path_ext, 1 }
+		'path_abs' { native_path_abs, 1 }
+		'path_rel' { native_path_rel, 2 }
+		'exec_full' { native_exec_full, 1 }
 		else { -1, 0 }
 	}
 }
@@ -1377,3 +1415,225 @@ fn (mut g Gen) new_label() string {
 fn (mut g Gen) emit_label(name string) {
 	g.labels[name] = g.code.len
 }
+
+// ---------------------------------------------------------------------------
+// closure capture analysis
+//
+// A closure (anonymous `fn`) may reference the enclosing function's locals.
+// Since the VM compiles each function with its own frame, those references
+// are resolved by capturing the values at closure-creation time: the compiler
+// scans the body for free variables, registers them as the lambda's leading
+// local slots, and emits loads of their current values before op_closure.
+
+// scan_captures returns the enclosing locals a closure body references, in
+// first-reference order (stable and deterministic for codegen).
+fn (mut g Gen) scan_captures(body []Stmt, fparams []string) []string {
+	mut bound := map[string]bool{}
+	for p in fparams {
+		bound[p] = true
+	}
+	mut caps := []string{}
+	mut seen := map[string]bool{}
+	for st in body {
+		g.scan_stmt(st, mut bound, mut caps, mut seen)
+	}
+	return caps
+}
+
+fn (mut g Gen) maybe_capture(name string, bound map[string]bool, mut caps []string, mut seen map[string]bool) {
+	if name in bound {
+		return // bound inside the closure — a plain local
+	}
+	if name !in g.locals {
+		return // not an enclosing local (global fn/const/enum — resolved elsewhere)
+	}
+	if name !in seen {
+		seen[name] = true
+		caps << name
+	}
+}
+
+fn (mut g Gen) scan_stmt(st Stmt, mut bound map[string]bool, mut caps []string, mut seen map[string]bool) {
+	match st.kind {
+		.expr_stmt {
+			g.scan_expr(st.expr, mut bound, mut caps, mut seen)
+		}
+		.let_stmt {
+			g.scan_expr(st.expr, mut bound, mut caps, mut seen)
+			bound[st.target] = true
+		}
+		.destruct_stmt {
+			g.scan_expr(st.expr, mut bound, mut caps, mut seen)
+			for t in st.destruct_targets {
+				bound[t] = true
+			}
+		}
+		.assign_stmt {
+			// assignment to a name that is not a closure-local references the
+			// enclosing local's captured copy
+			g.maybe_capture(st.target, bound, mut caps, mut seen)
+			bound[st.target] = true
+			g.scan_expr(st.expr, mut bound, mut caps, mut seen)
+		}
+		.index_assign {
+			g.scan_expr(st.base, mut bound, mut caps, mut seen)
+			g.scan_expr(st.idx, mut bound, mut caps, mut seen)
+			g.scan_expr(st.expr, mut bound, mut caps, mut seen)
+		}
+		.field_assign {
+			g.scan_expr(st.base, mut bound, mut caps, mut seen)
+			g.scan_expr(st.expr, mut bound, mut caps, mut seen)
+		}
+		.if_stmt {
+			g.scan_expr(st.cond, mut bound, mut caps, mut seen)
+			for s in st.body {
+				g.scan_stmt(s, mut bound, mut caps, mut seen)
+			}
+			for s in st.els {
+				g.scan_stmt(s, mut bound, mut caps, mut seen)
+			}
+		}
+		.match_stmt {
+			g.scan_expr(st.expr, mut bound, mut caps, mut seen)
+			for arm in st.arms {
+				g.scan_expr(arm.val, mut bound, mut caps, mut seen)
+				for s in arm.body {
+					g.scan_stmt(s, mut bound, mut caps, mut seen)
+				}
+			}
+			for s in st.els_body {
+				g.scan_stmt(s, mut bound, mut caps, mut seen)
+			}
+		}
+		.while_stmt {
+			g.scan_expr(st.cond, mut bound, mut caps, mut seen)
+			for s in st.body {
+				g.scan_stmt(s, mut bound, mut caps, mut seen)
+			}
+		}
+		.for_range_stmt {
+			g.scan_expr(st.expr, mut bound, mut caps, mut seen)
+			g.scan_expr(st.cond, mut bound, mut caps, mut seen)
+			had := st.target in bound
+			bound[st.target] = true
+			for s in st.body {
+				g.scan_stmt(s, mut bound, mut caps, mut seen)
+			}
+			if !had {
+				bound.delete(st.target)
+			}
+		}
+		.for_in_stmt {
+			g.scan_expr(st.expr, mut bound, mut caps, mut seen)
+			had := st.target in bound
+			bound[st.target] = true
+			mut had_idx := false
+			if st.idx_target.len > 0 {
+				had_idx = st.idx_target in bound
+				bound[st.idx_target] = true
+			}
+			for s in st.body {
+				g.scan_stmt(s, mut bound, mut caps, mut seen)
+			}
+			if !had {
+				bound.delete(st.target)
+			}
+			if st.idx_target.len > 0 && !had_idx {
+				bound.delete(st.idx_target)
+			}
+		}
+		.ret_stmt {
+			if st.has_val {
+				g.scan_expr(st.expr, mut bound, mut caps, mut seen)
+			}
+		}
+		.assert_stmt {
+			g.scan_expr(st.expr, mut bound, mut caps, mut seen)
+		}
+		.try_stmt {
+			for s in st.body {
+				g.scan_stmt(s, mut bound, mut caps, mut seen)
+			}
+			had := st.target in bound
+			bound[st.target] = true
+			for s in st.els {
+				g.scan_stmt(s, mut bound, mut caps, mut seen)
+			}
+			if !had {
+				bound.delete(st.target)
+			}
+		}
+		.throw_stmt {
+			g.scan_expr(st.expr, mut bound, mut caps, mut seen)
+		}
+		.break_stmt, .continue_stmt {}
+	}
+}
+
+fn (mut g Gen) scan_expr(e Expr, mut bound map[string]bool, mut caps []string, mut seen map[string]bool) {
+	match e.kind {
+		.ident {
+			g.maybe_capture(e.name, bound, mut caps, mut seen)
+		}
+		.call {
+			// a call to an enclosing local holding a closure must capture it too
+			g.maybe_capture(e.name, bound, mut caps, mut seen)
+			for a in e.args {
+				g.scan_expr(a, mut bound, mut caps, mut seen)
+			}
+		}
+		.field {
+			g.scan_expr(*e.left, mut bound, mut caps, mut seen)
+		}
+		.method_call {
+			g.scan_expr(*e.left, mut bound, mut caps, mut seen)
+			for a in e.args {
+				g.scan_expr(a, mut bound, mut caps, mut seen)
+			}
+		}
+		.index {
+			g.scan_expr(*e.left, mut bound, mut caps, mut seen)
+			g.scan_expr(*e.right, mut bound, mut caps, mut seen)
+		}
+		.slice {
+			g.scan_expr(*e.left, mut bound, mut caps, mut seen)
+			g.scan_expr(*e.right, mut bound, mut caps, mut seen)
+			g.scan_expr(*e.extra, mut bound, mut caps, mut seen)
+		}
+		.unary {
+			g.scan_expr(*e.right, mut bound, mut caps, mut seen)
+		}
+		.binary {
+			g.scan_expr(*e.left, mut bound, mut caps, mut seen)
+			g.scan_expr(*e.right, mut bound, mut caps, mut seen)
+		}
+		.array_lit {
+			for el in e.elems {
+				g.scan_expr(el, mut bound, mut caps, mut seen)
+			}
+		}
+		.struct_lit {
+			for f in e.fields {
+				g.scan_expr(f.val, mut bound, mut caps, mut seen)
+			}
+		}
+		.anon_fn {
+			// a nested closure: its parameters bind inside it, but references to
+			// enclosing locals still belong to this closure's capture set
+			mut saved := map[string]bool{}
+			for p in e.fparams {
+				saved[p] = p in bound
+				bound[p] = true
+			}
+			for s in e.fn_body {
+				g.scan_stmt(s, mut bound, mut caps, mut seen)
+			}
+			for p in e.fparams {
+				if !saved[p] {
+					bound.delete(p)
+				}
+			}
+		}
+		else {}
+	}
+}
diff --git a/compiler/lexer.v b/compiler/lexer.v
index 5b6f6bc..93389db 100644
--- a/compiler/lexer.v
+++ b/compiler/lexer.v
@@ -220,6 +220,11 @@ fn (mut l Lexer) next() !Tok {
 			return l.lex_number(line, col)
 		}
 		else {
+			// r"..." raw strings (no escape processing) — handy for regex
+			// patterns like r"\d+" that would otherwise need double escaping
+			if c == `r` && l.peek2() == `\"` {
+				return l.lex_raw_string(line, col)!
+			}
 			if (c >= `a` && c <= `z`) || (c >= `A` && c <= `Z`) || c == `_` {
 				return l.lex_ident(line, col)
 			}
@@ -310,6 +315,21 @@ fn (mut l Lexer) lex_ident(line int, col int) Tok {
 	return Tok{ kind: kind, lit: lit, line: line, col: col }
 }
 
+// lex_raw_string reads an r"..." string verbatim: backslashes, quotes and
+// ${...} sequences are all kept literally, so regex patterns pass through
+// untouched. The token is a plain str_lit whose content is the raw text.
+fn (mut l Lexer) lex_raw_string(line int, col int) !Tok {
+	l.advance() // 'r'
+	l.advance() // opening quote
+	start := l.pos
+	for l.pos < l.src.len {
+		if l.advance() == `\"` {
+			return Tok{ kind: .str_lit, lit: l.src[start..l.pos - 1], line: line, col: col }
+		}
+	}
+	return error('unterminated raw string at line ${line}, col ${col}')
+}
+
 fn (mut l Lexer) lex_string(line int, col int) !Tok {
 	l.advance() // opening quote
 	mut s := ''
diff --git a/compiler/opcodes.v b/compiler/opcodes.v
index 857e43e..ff9ce08 100644
--- a/compiler/opcodes.v
+++ b/compiler/opcodes.v
@@ -151,3 +151,24 @@ const native_now = 170
 const native_time_ms = 171
 const native_format_time = 172
 const native_parse_time = 173
+
+// regex builtins
+const native_regex_match = 174
+const native_regex_find_all = 175
+const native_regex_replace = 176
+const native_regex_split = 177
+
+// crypto/encoding builtins
+const native_base64_encode = 178
+const native_base64_decode = 179
+const native_sha256 = 180
+const native_md5 = 181
+const native_csv_parse = 182
+
+// extended HTTP + filesystem/process builtins
+const native_http_req = 183
+const native_path_ext = 184
+const native_path_abs = 185
+const native_path_rel = 186
+const native_exec_full = 187
+const native_weekday = 188
diff --git a/examples/stdlib.vr b/examples/stdlib.vr
new file mode 100644
index 0000000..29a1ef9
--- /dev/null
+++ b/examples/stdlib.vr
@@ -0,0 +1,102 @@
+// stdlib.vr — tests for the extended stdlib modules (regex, crypto, csv,
+// path/process helpers, date arithmetic). Run with `vr test examples/stdlib.vr`.
+
+import regex
+import crypto
+import csv
+import os
+import time
+import http
+
+fn test_regex() {
+	assert regex.is_match(r"^[a-z]+$", "hello") == 1
+	assert regex.is_match(r"^[a-z]+$", "Hello1") == 0
+	let nums = regex.find_all(r"\d+", "a1b22c333")
+	assert len(nums) == 3
+	assert nums[0] == "1"
+	assert nums[2] == "333"
+	assert regex.replace(r"\d+", "x1y22z", "#") == "x#y#z"
+	let parts = regex.split(r"[,;]", "a,b;c")
+	assert len(parts) == 3
+	assert parts[1] == "b"
+	// replacing a match in context (no group refs — use find_all for captures)
+	assert regex.replace(r"\d+", "id:42 name:bob", "#") == "id:# name:bob"
+	// invalid pattern throws (catchable)
+	try {
+		regex.is_match("([", "x")
+		assert false
+	} catch e {
+		assert len(e) > 0
+	}
+}
+
+fn test_crypto() {
+	assert crypto.sha256("hello") == "2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824"
+	assert crypto.md5("hello") == "5d41402abc4b2a76b9719d911017c592"
+	let enc = crypto.base64_encode("hello")
+	assert enc == "aGVsbG8="
+	assert crypto.base64_decode(enc) == "hello"
+	// hashes differ across inputs
+	assert crypto.sha256("a") != crypto.sha256("b")
+}
+
+fn test_csv() {
+	let rows = csv.parse("name,age\n\"amy, smith\",30\nbob,41")
+	assert len(rows) == 3
+	assert rows[0][0] == "name"
+	assert rows[1][0] == "amy, smith"
+	assert rows[2][1] == "41"
+	// empty input yields no rows
+	assert len(csv.parse("")) == 0
+}
+
+fn test_path_helpers() {
+	assert os.ext("a/b/file.txt") == ".txt"
+	assert os.ext("noext") == ""
+	assert os.base("a/b/c.vr") == "c.vr"
+	assert os.dir("a/b/c.vr") == "a/b"
+	assert os.rel("a/b/c.txt", "a") == "b/c.txt"
+	assert os.rel("a/b/c.txt", "a/b/c.txt") == "."
+	let abs_p = os.abs("main.v")
+	assert abs_p != "main.v"
+	assert len(abs_p) > 0
+}
+
+fn test_exec_full() {
+	let res = os.exec_full("echo hello-out; echo hello-err 1>&2")
+	assert res.code == 0
+	assert res.stdout == "hello-out\n"
+	assert res.stderr == "hello-err\n"
+	let bad = os.exec_full("exit 3")
+	assert bad.code == 3
+}
+
+fn test_time_arithmetic() {
+	let t = time.now()
+	assert time.add_days(t, 1) - t == 86400
+	assert time.add_hours(t, 2) - t == 7200
+	assert time.add_minutes(t, 5) - t == 300
+	assert time.add_seconds(t, 10) - t == 10
+	// 2026-08-25 was a Tuesday
+	let fixed = time.parse("2026-08-25 12:00:00")
+	assert time.weekday(fixed) == "Tue"
+	let later = time.add_days(fixed, 1)
+	assert time.date(later) == "2026-08-26"
+}
+
+fn test_http_headers_timeout() {
+	// offline-safe: connecting to a closed local port fails fast
+	try {
+		let h = { "X-Test": "1" }
+		http.request("GET", "http://127.0.0.1:1/nope", "", h, 500)
+		assert false
+	} catch e {
+		assert len(e) > 0
+	}
+	try {
+		http.get_timeout("http://127.0.0.1:1/nope", 500)
+		assert false
+	} catch e {
+		assert len(e) > 0
+	}
+}
diff --git a/examples/tests.vr b/examples/tests.vr
index ad669b2..02c25b8 100644
--- a/examples/tests.vr
+++ b/examples/tests.vr
@@ -319,7 +319,7 @@ fn test_module_imports() {
 	}
 	assert os.base("a/b/c.vr") == "c.vr"
 	assert os.dir("a/b/c.vr") == "a/b"
-	assert len(os.glob("lib/*.vr")) == 6
+	assert len(os.glob("lib/*.vr")) == 9
 	let tmp = os.join(os.cwd(), "tmp_test.txt")
 	os.write_lines(tmp, ["x", "y"])
 	assert len(os.read_lines(tmp)) == 2
@@ -455,6 +455,79 @@ fn test_time() {
 	}
 }
 
+fn test_closure_capture() {
+	// closures capture enclosing locals by value
+	let factor = 3
+	let dbl = fn(x) {
+		return x * factor
+	}
+	assert dbl(7) == 21
+
+	let name = "alice"
+	let age = 30
+	let greet = fn() {
+		return "hi " + name + " age=" + str(age)
+	}
+	assert greet() == "hi alice age=30"
+
+	// capture by value: later changes to the outer var don't affect the closure
+	let counter = 10
+	let read = fn() {
+		return counter
+	}
+	assert read() == 10
+	counter = 99
+	assert read() == 10
+
+	// nested closures capture through both levels
+	let base = 100
+	let outer = fn() {
+		let mid = 5
+		let inner = fn(x) {
+			return base + mid + x
+		}
+		return inner(1)
+	}
+	assert outer() == 106
+
+	// assignment to a captured variable writes the closure's own copy
+	let n = 1
+	let bump = fn() {
+		n = n + 1
+		return n
+	}
+	assert bump() == 2
+	assert n == 1
+
+	// closure stored in a struct, called dynamically
+	let handler = fn() {
+		return "handled"
+	}
+	let rec = { run: handler }
+	assert rec.run() == "handled"
+}
+
+fn test_dynamic_map_keys() {
+	// map keys may be computed expressions, not just string literals
+	let m = {}
+	for i in 0..3 {
+		m["key" + str(i)] = i * 10
+	}
+	assert m["key0"] == 0
+	assert m["key2"] == 20
+	let k = "key1"
+	assert m[k] == 10
+	assert has(m, "key1") == 1
+	assert len(m) == 3
+	delete(m, "key1")
+	assert has(m, "key1") == 0
+	assert len(m) == 2
+	// nested computed access
+	let cfg = { "db": { "host": "localhost", "port": 5432 } }
+	let which = "db"
+	assert cfg[which]["host"] == "localhost"
+}
+
 fn test_failing() {
 	// this one is meant to fail — shows up in `vr test` output
 	assert 1 == 2
diff --git a/extension/client/extension.js b/extension/client/extension.js
new file mode 100644
index 0000000..4f96823
--- /dev/null
+++ b/extension/client/extension.js
@@ -0,0 +1,53 @@
+// extension.js — VS Code client for the VuurRaaf language server.
+//
+// Spawns `vr lsp` (the toolchain's built-in language server) and wires up
+// diagnostics, go-to-definition, and hover for .vr / .vrmm files.
+// The toolchain binary defaults to `vr` on PATH; override it with the
+// `vuurraaf.toolchainPath` setting.
+
+const vscode = require('vscode');
+const {
+	LanguageClient,
+	TransportKind,
+} = require('vscode-languageclient/node');
+
+let client;
+
+function activate(context) {
+	const config = () => vscode.workspace.getConfiguration('vuurraaf');
+	const toolchain = () => config().get('toolchainPath', 'vr');
+
+	const serverOptions = {
+		command: toolchain(),
+		args: ['lsp'],
+		transport: TransportKind.stdio,
+	};
+
+	const clientOptions = {
+		documentSelector: [{ scheme: 'file', language: 'vuurraaf' }],
+		synchronize: {
+			// re-publish diagnostics when a settings change or a file is saved
+			fileEvents: vscode.workspace.createFileSystemWatcher('**/*.{vr,vrmm}'),
+		},
+	};
+
+	client = new LanguageClient('vuurraaf', 'VuurRaaf', serverOptions, clientOptions);
+	client.start();
+
+	context.subscriptions.push(
+		vscode.commands.registerCommand('vuurraaf.restartServer', async () => {
+			await client.stop();
+			client = new LanguageClient('vuurraaf', 'VuurRaaf', serverOptions, clientOptions);
+			client.start();
+			vscode.window.showInformationMessage('VuurRaaf language server restarted.');
+		})
+	);
+}
+
+function deactivate() {
+	if (client) {
+		return client.stop();
+	}
+}
+
+module.exports = { activate, deactivate };
diff --git a/extension/language-configuration.json b/extension/language-configuration.json
new file mode 100644
index 0000000..3e56cb8
--- /dev/null
+++ b/extension/language-configuration.json
@@ -0,0 +1,23 @@
+{
+	"comments": {
+		"lineComment": "//"
+	},
+	"brackets": [
+		["{", "}"],
+		["[", "]"],
+		["(", ")"]
+	],
+	"autoClosingPairs": [
+		{ "open": "{", "close": "}" },
+		{ "open": "[", "close": "]" },
+		{ "open": "(", "close": ")" },
+		{ "open": "\"", "close": "\"", "notIn": ["string"] },
+		{ "open": "'", "close": "'", "notIn": ["string", "comment"] }
+	],
+	"surroundingPairs": [
+		["{", "}"],
+		["[", "]"],
+		["(", ")"],
+		["\"", "\""]
+	]
+}
diff --git a/extension/package.json b/extension/package.json
new file mode 100644
index 0000000..5ae206a
--- /dev/null
+++ b/extension/package.json
@@ -0,0 +1,61 @@
+{
+	"name": "vuurraaf",
+	"displayName": "VuurRaaf",
+	"description": "Language support for VuurRaaf: syntax highlighting, diagnostics, and go-to-definition via the vr language server.",
+	"version": "0.1.0",
+	"publisher": "vuurraaf",
+	"license": "MIT",
+	"engines": {
+		"vscode": "^1.75.0"
+	},
+	"categories": [
+		"Programming Languages",
+		"Linters"
+	],
+	"activationEvents": [
+		"onLanguage:vuurraaf"
+	],
+	"main": "./client/extension.js",
+	"contributes": {
+		"languages": [
+			{
+				"id": "vuurraaf",
+				"aliases": [
+					"VuurRaaf",
+					"vr"
+				],
+				"extensions": [
+					".vr",
+					".vrmm"
+				],
+				"configuration": "./language-configuration.json"
+			}
+		],
+		"grammars": [
+			{
+				"language": "vuurraaf",
+				"scopeName": "source.vuurraaf",
+				"path": "./syntaxes/vuurraaf.tmLanguage.json"
+			}
+		],
+		"configuration": {
+			"title": "VuurRaaf",
+			"properties": {
+				"vuurraaf.toolchainPath": {
+					"type": "string",
+					"default": "vr",
+					"description": "Path to the vr toolchain binary (defaults to `vr` on PATH)."
+				}
+			}
+		}
+	},
+	"scripts": {
+		"vscode:prepublish": "npm install"
+	},
+	"dependencies": {
+		"vscode-languageclient": "^8.1.0"
+	},
+	"devDependencies": {
+		"@types/vscode": "^1.75.0"
+	}
+}
diff --git a/extension/syntaxes/vuurraaf.tmLanguage.json b/extension/syntaxes/vuurraaf.tmLanguage.json
new file mode 100644
index 0000000..fe1fd7b
--- /dev/null
+++ b/extension/syntaxes/vuurraaf.tmLanguage.json
@@ -0,0 +1,160 @@
+{
+	"$schema": "https://raw.githubusercontent.com/martinring/tmlanguage/master/tmlanguage.json",
+	"name": "VuurRaaf",
+	"scopeName": "source.vuurraaf",
+	"patterns": [
+		{
+			"include": "#comments"
+		},
+		{
+			"include": "#strings"
+		},
+		{
+			"include": "#numbers"
+		},
+		{
+			"include": "#keywords"
+		},
+		{
+			"include": "#function-declaration"
+		},
+		{
+			"include": "#function-call"
+		},
+		{
+			"include": "#identifiers"
+		},
+		{
+			"include": "#operators"
+		}
+	],
+	"repository": {
+		"comments": {
+			"patterns": [
+				{
+					"name": "comment.line.double-slash.vuurraaf",
+					"match": "//.*$"
+				}
+			]
+		},
+		"strings": {
+			"patterns": [
+				{
+					"name": "string.quoted.raw.vuurraaf",
+					"begin": "r\"",
+					"end": "\"",
+					"patterns": [
+						{
+							"name": "constant.character.escape.vuurraaf",
+							"match": "\\\\(\\\\|n|t|r|\"|$)"
+						}
+					]
+				},
+				{
+					"name": "string.quoted.double.vuurraaf",
+					"begin": "\"",
+					"end": "\"",
+					"patterns": [
+						{
+							"name": "constant.character.escape.vuurraaf",
+							"match": "\\\\(\\\\|n|t|r|\"|$)"
+						},
+						{
+							"name": "string.interpolated.vuurraaf",
+							"begin": "\\$\\{",
+							"end": "\\}",
+							"patterns": [
+								{
+									"include": "#identifiers"
+								}
+							]
+						}
+					]
+				}
+			]
+		},
+		"numbers": {
+			"patterns": [
+				{
+					"name": "constant.numeric.vuurraaf",
+					"match": "\\b(0x[0-9a-fA-F]+|\\d+(\\.\\d+)?([eE][+-]?\\d+)?)\\b"
+				}
+			]
+		},
+		"keywords": {
+			"patterns": [
+				{
+					"name": "keyword.control.vuurraaf",
+					"match": "\\b(fn|struct|enum|interface|import|const|let|if|else|while|for|in|match|break|continue|return|assert|try|catch|throw|and|or|not|true|false|none)\\b"
+				}
+			]
+		},
+		"function-declaration": {
+			"patterns": [
+				{
+					"name": "meta.function.vuurraaf",
+					"begin": "\\b(fn)\\s+([a-zA-Z_][a-zA-Z0-9_]*)\\s*\\(",
+					"beginCaptures": {
+						"1": {
+							"name": "keyword.control.vuurraaf"
+						},
+						"2": {
+							"name": "entity.name.function.vuurraaf"
+						}
+					},
+					"end": "\\)",
+					"patterns": [
+						{
+							"include": "#identifiers"
+						}
+					]
+				}
+			]
+		},
+		"function-call": {
+			"patterns": [
+				{
+					"name": "meta.function-call.vuurraaf",
+					"begin": "\\b([a-zA-Z_][a-zA-Z0-9_]*)\\s*\\(",
+					"beginCaptures": {
+						"1": {
+							"name": "entity.name.function.vuurraaf"
+						}
+					},
+					"end": "\\)",
+					"patterns": [
+						{
+							"include": "#identifiers"
+						},
+						{
+							"include": "#numbers"
+						},
+						{
+							"include": "#strings"
+						}
+					]
+				}
+			]
+		},
+		"identifiers": {
+			"patterns": [
+				{
+					"name": "entity.name.type.vuurraaf",
+					"match": "\\b[A-Z][a-zA-Z0-9_]*\\b"
+				},
+				{
+					"name": "variable.other.vuurraaf",
+					"match": "\\b[a-z_][a-zA-Z0-9_]*\\b"
+				}
+			]
+		},
+		"operators": {
+			"patterns": [
+				{
+					"name": "keyword.operator.vuurraaf",
+					"match": "==|!=|<=|>=|<<|>>|\\+|\\-|\\*|/|%|&|\\||\\^|~|=|<|>"
+				}
+			]
+		}
+	}
+}
diff --git a/lib/crypto.vr b/lib/crypto.vr
new file mode 100644
index 0000000..241f71b
--- /dev/null
+++ b/lib/crypto.vr
@@ -0,0 +1,23 @@
+// crypto.vr — hashing and encoding (part of the VuurRaaf stdlib).
+//
+//   import crypto
+//   println(crypto.sha256("hello"))
+//   println(crypto.md5("hello"))
+//   println(crypto.base64_encode("hello"))   // aGVsbG8=
+//   println(crypto.base64_decode("aGVsbG8="))
+
+fn sha256(s) {
+	return sha256(s)
+}
+
+fn md5(s) {
+	return md5(s)
+}
+
+fn base64_encode(s) {
+	return base64_encode(s)
+}
+
+fn base64_decode(s) {
+	return base64_decode(s)
+}
diff --git a/lib/csv.vr b/lib/csv.vr
new file mode 100644
index 0000000..bf2b3d3
--- /dev/null
+++ b/lib/csv.vr
@@ -0,0 +1,13 @@
+// csv.vr — comma-separated values parsing (part of the VuurRaaf stdlib).
+//
+//   import csv
+//   let rows = csv.parse("name,age\namy,30\nbob,41")
+//   // rows == [["name", "age"], ["amy", "30"], ["bob", "41"]]
+//   println(rows[1][0])   // amy
+//
+// parse returns an array of rows; each row is an array of cell strings.
+// Quoted fields, embedded commas and newlines are handled.
+
+fn parse(s) {
+	return csv_parse(s)
+}
diff --git a/lib/http.vr b/lib/http.vr
index 30dd0e6..3a74c16 100644
--- a/lib/http.vr
+++ b/lib/http.vr
@@ -21,3 +21,26 @@ fn post(url, data) {
 fn get_text(url) {
 	return http_get(url).body
 }
+
+// request sends any method with custom headers (a {name: value} struct) and
+// a timeout in milliseconds, and returns {status, body}. A timeout <= 0 uses
+// the default (30s). Network failures throw; HTTP errors are normal responses.
+fn request(method, url, data, headers, timeout_ms) {
+	return http_req(method, url, data, headers, timeout_ms)
+}
+
+fn get_with_headers(url, headers) {
+	return http_req("GET", url, "", headers, 0)
+}
+
+fn post_with_headers(url, data, headers) {
+	return http_req("POST", url, data, headers, 0)
+}
+
+fn get_timeout(url, timeout_ms) {
+	return http_req("GET", url, "", {}, timeout_ms)
+}
+
+fn post_timeout(url, data, timeout_ms) {
+	return http_req("POST", url, data, {}, timeout_ms)
+}
diff --git a/lib/os.vr b/lib/os.vr
index 5830bc2..6c0ff45 100644
--- a/lib/os.vr
+++ b/lib/os.vr
@@ -73,3 +73,23 @@ fn env(name) {
 fn exec(cmd) {
 	return build_exec(cmd)
 }
+
+// ext returns the file extension including the dot ("file.txt" -> ".txt").
+fn ext(path) {
+	return path_ext(path)
+}
+
+// abs converts a path to an absolute one.
+fn abs(path) {
+	return path_abs(path)
+}
+
+// rel returns path relative to base ("a/b/c.txt" relative to "a" -> "b/c.txt").
+fn rel(path, base) {
+	return path_rel(path, base)
+}
+
+// exec_full runs a shell command and returns {code, stdout, stderr}.
+fn exec_full(cmd) {
+	return exec_full(cmd)
+}
diff --git a/lib/regex.vr b/lib/regex.vr
new file mode 100644
index 0000000..3893de2
--- /dev/null
+++ b/lib/regex.vr
@@ -0,0 +1,30 @@
+// regex.vr — regular expressions (part of the VuurRaaf stdlib).
+//
+//   import regex
+//   if regex.match(r"^[a-z]+$", "hello") {
+//       println("all lowercase")
+//   }
+//   for m in regex.find_all(r"\d+", "a1b22c333") {
+//       println(m)   // "1", "22", "333"
+//   }
+//
+// Patterns use RE2 syntax (no backreferences). Invalid patterns throw and
+// can be caught with try/catch.
+
+fn is_match(pattern, s) {
+	return regex_match(pattern, s)
+}
+
+// find_all returns an array of every substring that matches the pattern.
+fn find_all(pattern, s) {
+	return regex_find_all(pattern, s)
+}
+
+// replace substitutes every match with `repl`.
+fn replace(pattern, s, repl) {
+	return regex_replace(pattern, s, repl)
+}
+
+fn split(pattern, s) {
+	return regex_split(pattern, s)
+}
diff --git a/lib/time.vr b/lib/time.vr
index 52c9126..7c07dda 100644
--- a/lib/time.vr
+++ b/lib/time.vr
@@ -34,3 +34,26 @@ fn date(t) {
 fn clock(t) {
 	return format_time(t, "HH:mm:ss")
 }
+
+// weekday(t) returns the day of the week, e.g. "Mon", "Tue", ... "Sun".
+fn weekday(t) {
+	return weekday(t)
+}
+
+// --- date arithmetic (all values are Unix epoch seconds) ---
+
+fn add_seconds(t, n) {
+	return t + n
+}
+
+fn add_minutes(t, n) {
+	return t + n * 60
+}
+
+fn add_hours(t, n) {
+	return t + n * 3600
+}
+
+fn add_days(t, n) {
+	return t + n * 86400
+}
diff --git a/lsp.v b/lsp.v
new file mode 100644
index 0000000..9aa4c76
--- /dev/null
+++ b/lsp.v
@@ -0,0 +1,537 @@
+// lsp.v — a minimal Language Server Protocol server for VuurRaaf.
+//
+//   vr lsp
+//
+// Speaks JSON-RPC 2.0 over stdio with Content-Length framing. The editor
+// (see extension/ for a VS Code client) sends the open document, and the
+// server replies with:
+//   - diagnostics: the compiler's first error, positioned via its line/col
+//   - go-to-definition: jumps to function/struct/enum/const/let declarations
+//     in the current file (and stdlib module functions)
+//   - hover: the kind of the symbol under the cursor
+//
+// Text sync is "full document" (version 1), which keeps the client simple.
+
+module main
+
+import os
+import json2
+import compiler
+
+// stdio bindings used for the JSON-RPC transport (Content-Length framing)
+fn C.fgetc(stream voidptr) int
+fn C.fread(dest voidptr, size usize, count usize, stream voidptr) usize
+fn C.fwrite(src voidptr, size usize, count usize, stream voidptr) usize
+fn C.fflush(stream voidptr) int
+
+// ---------------------------------------------------------------------------
+// JSON-RPC framing
+
+struct LspParams {
+mut:
+	text_document     TextDocParam @[json: 'textDocument']
+	position          LspPosition
+	content_changes   []TextChangeParam @[json: 'contentChanges']
+}
+
+struct TextDocParam {
+mut:
+	uri     string
+	text    string
+	version int
+}
+
+struct LspPosition {
+mut:
+	line      int
+	character int
+}
+
+struct TextChangeParam {
+mut:
+	text string
+}
+
+struct LspMsg {
+mut:
+	jsonrpc string
+	id      int
+	method  string
+	params  LspParams
+}
+
+fn toolchain_lsp() {
+	run_lsp()
+}
+
+fn run_lsp() {
+	mut docs := map[string]string{} // uri -> latest text (full sync)
+	for {
+		raw := read_rpc() or { break }
+		if raw.len == 0 {
+			continue
+		}
+		handle_rpc(raw, mut docs)
+	}
+}
+
+fn handle_rpc(raw string, mut docs map[string]string) {
+	msg := json2.decode[LspMsg](raw) or { return }
+	match msg.method {
+		'initialize' {
+			// textDocumentSync 1 = full document sync
+			send_response(msg.id,
+				'{"capabilities":{"textDocumentSync":1,"definitionProvider":true,"hoverProvider":true}}')
+		}
+		'initialized' {
+			// notification — nothing to do
+		}
+		'shutdown' {
+			send_response(msg.id, 'null')
+		}
+		'exit' {
+			exit(0)
+		}
+		'textDocument/didOpen' {
+			docs[msg.params.text_document.uri] = msg.params.text_document.text
+			publish_diagnostics(msg.params.text_document.uri, msg.params.text_document.text)
+		}
+		'textDocument/didChange' {
+			// full sync: the last content change carries the whole document
+			if msg.params.content_changes.len > 0 {
+				docs[msg.params.text_document.uri] = msg.params.content_changes[msg.params.content_changes.len -
+					1].text
+			}
+			text := docs[msg.params.text_document.uri] or { '' }
+			publish_diagnostics(msg.params.text_document.uri, text)
+		}
+		'textDocument/didSave' {
+			text := docs[msg.params.text_document.uri] or { '' }
+			publish_diagnostics(msg.params.text_document.uri, text)
+		}
+		'textDocument/definition' {
+			loc := definition_at(msg.params.text_document.uri, docs, msg.params.position)
+			send_response(msg.id, loc)
+		}
+		'textDocument/hover' {
+			h := hover_at(msg.params.text_document.uri, docs, msg.params.position)
+			send_response(msg.id, h)
+		}
+		else {
+			// respond null to unknown requests so editors don't hang
+			if msg.id > 0 {
+				send_response(msg.id, 'null')
+			}
+		}
+	}
+}
+
+// read_rpc reads one Content-Length framed JSON-RPC message from stdin.
+fn read_rpc() !string {
+	mut content_len := 0
+	for {
+		line := read_stdin_line() or { return err }
+		if line.len == 0 {
+			break // blank line ends the header block
+		}
+		if line.starts_with('Content-Length:') {
+			content_len = line.all_after(':').trim_space().int()
+		}
+	}
+	if content_len <= 0 {
+		return ''
+	}
+	return read_stdin_bytes(content_len).bytestr()
+}
+
+fn read_stdin_line() !string {
+	mut line := []u8{}
+	for {
+		b := read_stdin_byte() or { return err }
+		if b == `\n` {
+			break
+		}
+		if b != `\r` {
+			line << b
+		}
+	}
+	return line.bytestr()
+}
+
+fn read_stdin_byte() !u8 {
+	c := unsafe { C.fgetc(C.stdin) }
+	if c == -1 {
+		return error('stdin closed')
+	}
+	return u8(c)
+}
+
+fn read_stdin_bytes(n int) []u8 {
+	mut buf := []u8{len: n}
+	if n > 0 {
+		unsafe {
+			C.fread(buf.data, 1, usize(n), C.stdin)
+		}
+	}
+	return buf
+}
+
+fn send_response(id int, result string) {
+	send_raw('{"jsonrpc":"2.0","id":${id},"result":${result}}')
+}
+
+fn send_raw(body string) {
+	header := 'Content-Length: ${body.len}\r\n\r\n'
+	unsafe {
+		C.fwrite(header.str, 1, usize(header.len), C.stdout)
+		C.fwrite(body.str, 1, usize(body.len), C.stdout)
+		C.fflush(C.stdout)
+	}
+}
+
+// ---------------------------------------------------------------------------
+// diagnostics
+
+fn publish_diagnostics(uri string, text string) {
+	diags := collect_diagnostics(text)
+	send_raw('{"jsonrpc":"2.0","method":"textDocument/publishDiagnostics","params":{"uri":"${json_escape(uri)}","diagnostics":[${diags}]}}')
+}
+
+// collect_diagnostics runs the compiler over `text` and renders the first
+// error as an LSP diagnostic. Returns the diagnostics array body (or empty).
+fn collect_diagnostics(text string) string {
+	_ = compiler.compile(text) or {
+		mut line, mut col := extract_pos(err.msg())
+		if line < 1 {
+			line = 1
+		}
+		start_line := line - 1
+		msg := json_escape(err.msg())
+		return '{"range":{"start":{"line":${start_line},"character":${col}},"end":{"line":${start_line},"character":${col + 1}}},"severity":1,"source":"vr","message":"${msg}"}'
+	}
+	return ''
+}
+
+// extract_pos pulls "line N[, col M]" out of a compiler error message.
+// The toolchain's errors are formatted as `... at line 12, col 5`,
+// `... at line 12` or `... (line 12)`.
+fn extract_pos(msg string) (int, int) {
+	mut line := 0
+	mut col := 0
+	if start := msg.index('line ') {
+		mut i := start + 5
+		mut num := ''
+		for i < msg.len && msg[i] >= `0` && msg[i] <= `9` {
+			num += msg[i].ascii_str()
+			i++
+		}
+		if num.len > 0 {
+			line = num.int()
+		}
+		if c := msg.index('col ') {
+			mut j := c + 4
+			mut cnum := ''
+			for j < msg.len && msg[j] >= `0` && msg[j] <= `9` {
+				cnum += msg[j].ascii_str()
+				j++
+			}
+			if cnum.len > 0 {
+				col = cnum.int()
+			}
+		}
+	}
+	return line, col
+}
+
+// ---------------------------------------------------------------------------
+// symbols (definition + hover)
+
+// symbol_at resolves the identifier under the cursor and returns its kind and
+// definition line, looking in the current document and then in imported
+// stdlib modules.
+fn symbol_at(uri string, docs map[string]string, pos LspPosition) (string, int, string) {
+	text := docs[uri] or { return '', 0, '' }
+	word := word_at(text, pos)
+	if word.len == 0 {
+		return '', 0, ''
+	}
+	line, kind, ok := find_symbol(text, word)
+	if ok {
+		return uri, line, kind
+	}
+	// module call: the cursor may sit on the module part ("os" in "os.exists")
+	// or the function part ("exists"). Look up imported modules either way.
+	mut mod_name := ''
+	mut fn_name := word
+	if word.contains('.') {
+		parts := word.split('.')
+		if parts.len == 2 {
+			mod_name = parts[0]
+			fn_name = parts[1]
+		}
+	} else {
+		// cursor on the module part: extend to the dotted name
+		if pos.character > 0 && pos.character < text.len {
+			if e := word_at_ext(text, pos) {
+				parts := e.split('.')
+				if parts.len == 2 && parts[0] == word {
+					mod_name = parts[0]
+					fn_name = parts[1]
+				}
+			}
+		}
+	}
+	if mod_name.len > 0 {
+		if path := compiler.resolve_import(mod_name) {
+			src := os.read_file(path) or { return '', 0, '' }
+			l2, k2, ok2 := find_symbol(src, fn_name)
+			if ok2 {
+				return 'file://${path}', l2, k2
+			}
+		}
+	}
+	// bare function name: search every module this file imports
+	for m in imported_modules(text) {
+		if path := compiler.resolve_import(m) {
+			src := os.read_file(path) or { continue }
+			l2, k2, ok2 := find_symbol(src, word)
+			if ok2 {
+				return 'file://${path}', l2, k2
+			}
+		}
+	}
+	return '', 0, ''
+}
+
+// word_at_ext returns the dotted identifier starting at `pos` when the cursor
+// is on the module part of a call like os.exists (word_at alone would stop
+// at the dot).
+fn word_at_ext(text string, pos LspPosition) ?string {
+	mut line_i := 0
+	for l in text.split('\n') {
+		if line_i == pos.line {
+			if pos.character < 0 || pos.character > l.len {
+				return none
+			}
+			// scan back to the start of the dotted identifier
+			mut start := pos.character
+			for start > 0 && (is_ident_char(l[start - 1]) || l[start - 1] == `.`) {
+				start--
+			}
+			mut end := pos.character
+			for end < l.len && (is_ident_char(l[end]) || l[end] == `.`) {
+				end++
+			}
+			if start == end {
+				return none
+			}
+			return l[start..end]
+		}
+		line_i++
+	}
+	return none
+}
+
+// imported_modules returns the bare module names (`import os`) in a file.
+fn imported_modules(text string) []string {
+	toks := compiler.tokenize(text) or { return []string{} }
+	prog := compiler.parse(toks) or { return []string{} }
+	mut out := []string{}
+	for imp in prog.imports {
+		if imp.name.len > 0 {
+			out << imp.name
+		}
+	}
+	return out
+}
+
+fn definition_at(uri string, docs map[string]string, pos LspPosition) string {
+	loc_uri, line, _ := symbol_at(uri, docs, pos)
+	if loc_uri.len == 0 {
+		return 'null'
+	}
+	return location_json(loc_uri, line)
+}
+
+fn hover_at(uri string, docs map[string]string, pos LspPosition) string {
+	_, line, kind := symbol_at(uri, docs, pos)
+	if line == 0 {
+		return 'null'
+	}
+	return '{"contents":{"kind":"markdown","value":"**${kind}** at line ${line}"}}'
+}
+
+fn location_json(uri string, line int) string {
+	// 1-based source line → 0-based LSP position; character 0 (we only track lines)
+	return '{"uri":"${json_escape(uri)}","range":{"start":{"line":${line - 1},"character":0},"end":{"line":${line - 1},"character":0}}}'
+}
+
+// word_at returns the identifier covering the given position in `text`.
+fn word_at(text string, pos LspPosition) string {
+	mut line_i := 0
+	for l in text.split('\n') {
+		if line_i == pos.line {
+			if pos.character < 0 || pos.character > l.len {
+				return ''
+			}
+			mut start := pos.character
+			mut end := pos.character
+			for start > 0 && is_ident_char(l[start - 1]) {
+				start--
+			}
+			for end < l.len && is_ident_char(l[end]) {
+				end++
+			}
+			if start == end {
+				return ''
+			}
+			return l[start..end]
+		}
+		line_i++
+	}
+	return ''
+}
+
+fn is_ident_char(c u8) bool {
+	lo := c >= `a` && c <= `z`
+	hi := c >= `A` && c <= `Z`
+	dig := c >= `0` && c <= `9`
+	return lo || hi || dig || c == `_`
+}
+
+// find_symbol parses VuurRaaf source and locates the definition line and kind
+// of a named symbol (functions, structs, enums, constants, locals, params).
+fn find_symbol(src string, name string) (int, string, bool) {
+	toks := compiler.tokenize(src) or { return 0, '', false }
+	prog := compiler.parse(toks) or { return 0, '', false }
+	mut line := 0
+	mut kind := ''
+	for fd in prog.fns {
+		if fd.name == name {
+			return fd.line, 'function', true
+		}
+		for p in fd.params {
+			if p == name {
+				line = fd.line
+				kind = 'parameter'
+			}
+		}
+	}
+	for sd in prog.structs {
+		if sd.name == name {
+			return sd.line, 'struct', true
+		}
+	}
+	for ed in prog.enums {
+		if ed.name == name {
+			return ed.line, 'enum', true
+		}
+	}
+	for cd in prog.consts {
+		if cd.name == name {
+			return cd.line, 'constant', true
+		}
+	}
+	for fd in prog.fns {
+		for st in fd.body {
+			l, k, ok := find_symbol_stmt(st, name)
+			if ok {
+				line = l
+				kind = k
+			}
+		}
+	}
+	if line > 0 {
+		return line, kind, true
+	}
+	return 0, '', false
+}
+
+fn find_symbol_stmt(st compiler.Stmt, name string) (int, string, bool) {
+	match st.kind {
+		.let_stmt {
+			if st.target == name {
+				return st.line, 'variable', true
+			}
+		}
+		.destruct_stmt {
+			for t in st.destruct_targets {
+				if t == name {
+					return st.line, 'variable', true
+				}
+			}
+		}
+		.for_range_stmt, .for_in_stmt {
+			if st.target == name {
+				return st.line, 'loop variable', true
+			}
+			if st.idx_target == name {
+				return st.line, 'loop variable', true
+			}
+		}
+		.try_stmt {
+			if st.target == name {
+				return st.line, 'catch variable', true
+			}
+		}
+		else {}
+	}
+	// recurse into nested statements so inner blocks are covered too
+	for s in st.body {
+		l, k, ok := find_symbol_stmt(s, name)
+		if ok {
+			return l, k, true
+		}
+	}
+	for s in st.els {
+		l, k, ok := find_symbol_stmt(s, name)
+		if ok {
+			return l, k, true
+		}
+	}
+	for s in st.els_body {
+		l, k, ok := find_symbol_stmt(s, name)
+		if ok {
+			return l, k, true
+		}
+	}
+	for arm in st.arms {
+		for s in arm.body {
+			l, k, ok := find_symbol_stmt(s, name)
+			if ok {
+				return l, k, true
+			}
+		}
+	}
+	return 0, '', false
+}
+
+// ---------------------------------------------------------------------------
+// helpers
+
+fn json_escape(s string) string {
+	mut out := ''
+	for c in s {
+		match c {
+			`"` {
+				out += '\\"'
+			}
+			`\\` {
+				out += '\\\\'
+			}
+			`\n` {
+				out += '\\n'
+			}
+			`\r` {
+				out += '\\r'
+			}
+			`\t` {
+				out += '\\t'
+			}
+			else {
+				out += c.ascii_str()
+			}
+		}
+	}
+	return out
+}
diff --git a/main.v b/main.v
index f63f109..86bf39d 100644
--- a/main.v
+++ b/main.v
@@ -73,6 +73,9 @@ fn main() {
 		'repl', 'i' {
 			toolchain_repl() or { die('repl', err) }
 		}
+		'lsp' {
+			toolchain_lsp()
+		}
 		'fmt' {
 			toolchain_fmt(rest) or { die('fmt', err) }
 		}
@@ -190,6 +193,7 @@ fn toolchain_help() {
 	println('  test <file.vr>                           run every test_* function')
 	println('  bench <file.vr> [iterations]             benchmark main()')
 	println('  repl                                     interactive session')
+	println('  lsp                                      language server (JSON-RPC over stdio)')
 	println('  fmt [-w] <file.vr>                       format source')
 	println('  init [name]                              scaffold a project')
 	println('  get <owner/repo | url | ./path>          fetch a package into vendor/')
@@ -358,10 +362,23 @@ fn toolchain_link(args []string) ! {
 
 fn toolchain_run(args []string) ! {
 	if args.len == 0 {
-		return error('usage: vr run <file.vr|file.vbin> [program-args...]')
+		return error('usage: vr run <file.vr|file.vbin> [program-args...]  (add -w to watch for changes)')
+	}
+	mut watch := false
+	mut rest := args.clone()
+	if rest[0] == '-w' || rest[0] == '--watch' {
+		watch = true
+		rest = rest[1..]
+	}
+	if rest.len == 0 {
+		return error('usage: vr run <file.vr|file.vbin> [program-args...]  (add -w to watch for changes)')
+	}
+	f := rest[0]
+	prog_args := rest[1..]
+	if watch {
+		run_watch(f, prog_args)!
+		return
 	}
-	f := args[0]
-	prog_args := args[1..]
 	if f.ends_with('.vbin') {
 		bin := obj.read_bin(f)!
 		vm.run_with_args(bin, 'main', false, prog_args)!
@@ -374,6 +391,32 @@ fn toolchain_run(args []string) ! {
 	return error('unsupported file type: ${f} (expected .vr or .vbin)')
 }
 
+// run_watch recompiles and reruns the program whenever the source file (or
+// anything it imports) changes — the classic develop-run-edit loop.
+fn run_watch(f string, prog_args []string) ! {
+	if !f.ends_with('.vr') {
+		return error('watch mode works on .vr source files, got ${f}')
+	}
+	mut last := os.file_last_mod_unix(f)
+	println('watching ${f} (Ctrl-C to stop)')
+	for {
+		// clear the screen between runs for a clean diff of output
+		print('\x1b[2J\x1b[H')
+		println('== ${os.file_name(f)} — ${time.now().custom_format('HH:mm:ss')} ==')
+		run_src_with_args(f, 'main', false, prog_args) or {
+			eprintln('${err.msg()}')
+		}
+		for {
+			time.sleep(400 * time.millisecond)
+			cur := os.file_last_mod_unix(f)
+			if cur != last {
+				last = cur
+				break
+			}
+		}
+	}
+}
+
 fn toolchain_debug(args []string) ! {
 	if args.len == 0 {
 		return error('usage: vr debug <file.vr|file.vbin>')
@@ -394,9 +437,14 @@ fn toolchain_debug(args []string) ! {
 
 fn toolchain_test(args []string) ! {
 	if args.len == 0 {
-		return error('usage: vr test <file.vr>')
+		return error('usage: vr test <file.vr|dir>')
 	}
-	src := args[0]
+	target := args[0]
+	if os.is_dir(target) {
+		test_dir(target)!
+		return
+	}
+	src := target
 	o := compiler.compile_file(src)!
 	mut tests := []string{}
 	for s in o.symbols {
@@ -434,6 +482,60 @@ fn toolchain_test(args []string) ! {
 	}
 }
 
+// test_dir runs every test_* function in every .vr file under a directory
+// (recursively), so a whole project's suite runs with one command.
+fn test_dir(dir string) ! {
+	files := os.walk_ext(dir, '.vr', os.WalkParams{})
+	mut files_sorted := files.clone()
+	files_sorted.sort()
+	mut total_pass := 0
+	mut total_fail := 0
+	mut file_count := 0
+	for src in files_sorted {
+		if os.file_name(src).starts_with('.') {
+			continue
+		}
+		o := compiler.compile_file(src) or {
+			eprintln('  COMPILE FAIL  ${src}  —  ${err.msg()}')
+			total_fail++
+			continue
+		}
+		mut tests := []string{}
+		for s in o.symbols {
+			if s.name.starts_with('test_') {
+				tests << s.name
+			}
+		}
+		if tests.len == 0 {
+			continue
+		}
+		file_count++
+		println('-- ${src}')
+		tmp_obj := os.join_path(os.temp_dir(), 'vr_${os.getpid()}_${file_count}.vobj')
+		tmp_bin := os.join_path(os.temp_dir(), 'vr_${os.getpid()}_${file_count}.vbin')
+		defer {
+			os.rm(tmp_obj) or {}
+			os.rm(tmp_bin) or {}
+		}
+		obj.write(tmp_obj, o)!
+		linker.link([tmp_obj], tmp_bin)!
+		bin := obj.read_bin(tmp_bin)!
+		for t in tests {
+			if run_test(bin, t) {
+				println('  PASS  ${t}')
+				total_pass++
+			} else {
+				total_fail++
+			}
+		}
+	}
+	println('')
+	println('${total_pass} passed, ${total_fail} failed across ${file_count} file(s)')
+	if total_fail > 0 {
+		exit(1)
+	}
+}
+
 fn run_test(bin obj.Bin, name string) bool {
 	vm.run(bin, name, false) or {
 		eprintln('  FAIL  ${name}  —  ${err}')
diff --git a/vm/gc.v b/vm/gc.v
index 95c61a2..724e91e 100644
--- a/vm/gc.v
+++ b/vm/gc.v
@@ -84,6 +84,13 @@ fn (mut v Vm) collect() {
 			}
 		}
 	}
+	for h in 0..v.closures.len {
+		if closure_mark[h] {
+			for j in 0..v.closures[h].captured.len {
+				v.closures[h].captured[j] = v.remap(v.closures[h].captured[j], str_new, arr_new, struct_new, float_new, closure_new)
+			}
+		}
+	}
 	// ---- compact pools ----
 	mut strings := v.strings[..v.const_strs]
 	for i in v.const_strs..v.strings.len {
@@ -164,6 +171,9 @@ fn (mut v Vm) mark_value(x i64, mut str_mark []bool, mut arr_mark []bool, mut st
 				h := v.hand(val)
 				if h >= 0 && h < closure_mark.len && !closure_mark[h] {
 					closure_mark[h] = true
+					for cv in v.closures[h].captured {
+						work << cv
+					}
 				}
 			}
 			else {}
diff --git a/vm/json.v b/vm/json.v
index b04dfe1..ffa2c5f 100644
--- a/vm/json.v
+++ b/vm/json.v
@@ -113,7 +113,7 @@ fn (mut v Vm) json_parse_object(mut p JsonParser) !i64 {
 	p.skip_ws()
 	if p.peek() == `}` {
 		p.pos++
-		v.structs << StructVal{ fields: fields }
+		v.structs << StructVal{ fields: fields, by_name: v.index_fields(fields) }
 		return v.mkstruct_handle(v.structs.len - 1)
 	}
 	for {
@@ -152,7 +152,7 @@ fn (mut v Vm) json_parse_object(mut p JsonParser) !i64 {
 		}
 		return p.error('expected "," or "}" in object')
 	}
-	v.structs << StructVal{ fields: fields }
+	v.structs << StructVal{ fields: fields, by_name: v.index_fields(fields) }
 	return v.mkstruct_handle(v.structs.len - 1)
 }
 
diff --git a/vm/native.v b/vm/native.v
index 9041900..e601383 100644
--- a/vm/native.v
+++ b/vm/native.v
@@ -16,6 +16,11 @@ import obj
 import compiler
 import assembler
 import linker
+import regex
+import encoding.base64
+import crypto.sha256
+import crypto.md5
+import encoding.csv
 
 fn (mut v Vm) native(id int, _argc int) ! {
 	match id {
@@ -248,11 +253,11 @@ fn (mut v Vm) native(id int, _argc int) ! {
 			if v.is_arr(x) && v.valid_arr_handle(x) {
 				v.arrays << v.arrays[v.hand(x)].clone()
 				v.push(v.mkarr(v.arrays.len - 1))!
-			} else if v.is_struct(x) && v.valid_struct_handle(x) {
-				s := v.structs[v.hand(x)]
-				v.structs << StructVal{ fields: s.fields.clone() }
-				v.push(v.mkstruct_handle(v.structs.len - 1))!
-			} else if v.is_str(x) && v.valid_handle(x) {
+		} else if v.is_struct(x) && v.valid_struct_handle(x) {
+			s := v.structs[v.hand(x)]
+			v.structs << StructVal{ fields: s.fields.clone(), by_name: s.by_name.clone() }
+			v.push(v.mkstruct_handle(v.structs.len - 1))!
+		} else if v.is_str(x) && v.valid_handle(x) {
 				v.push(v.alloc_str(v.strings[v.hand(x)]))!
 			} else if v.is_float(x) {
 				v.push(v.push_float(v.fval(x)))!
@@ -679,12 +684,208 @@ fn (mut v Vm) native(id int, _argc int) ! {
 			t := time.parse(s) or { return error('parse_time: ${err.msg()}') }
 			v.push(v.enc_int(t.unix()))!
 		}
+		native_weekday {
+			t := v.dec_int(v.pop()!)
+			v.push(v.alloc_str(time.unix(t).weekday_str()))!
+		}
+		// -------------------------------------------------------------------
+		// regex — RE2-style patterns via V's regex module. Every call compiles
+		// the pattern fresh; the VuurRaaf-level module can cache if it needs to.
+		native_regex_match {
+			s := v.pop_str()!
+			pat := v.pop_str()!
+			mut re := regex.regex_opt(pat) or { return error('regex: ${err.msg()}') }
+			v.push(v.enc_int(bool_i64(re.matches_string(s))))!
+		}
+		native_regex_find_all {
+			s := v.pop_str()!
+			pat := v.pop_str()!
+			mut re := regex.regex_opt(pat) or { return error('regex: ${err.msg()}') }
+			matches := re.find_all_str(s)
+			mut arr := []i64{}
+			for m in matches {
+				v.strings << m
+				arr << v.mkstr(v.strings.len - 1)
+			}
+			v.arrays << arr
+			v.push(v.mkarr(v.arrays.len - 1))!
+		}
+		native_regex_replace {
+			repl := v.pop_str()!
+			s := v.pop_str()!
+			pat := v.pop_str()!
+			mut re := regex.regex_opt(pat) or { return error('regex: ${err.msg()}') }
+			v.push(v.alloc_str(re.replace(s, repl)))!
+		}
+		native_regex_split {
+			s := v.pop_str()!
+			pat := v.pop_str()!
+			mut re := regex.regex_opt(pat) or { return error('regex: ${err.msg()}') }
+			parts := re.split(s)
+			mut arr := []i64{}
+			for p in parts {
+				v.strings << p
+				arr << v.mkstr(v.strings.len - 1)
+			}
+			v.arrays << arr
+			v.push(v.mkarr(v.arrays.len - 1))!
+		}
+		// -------------------------------------------------------------------
+		// base64 + hashes
+		native_base64_encode {
+			s := v.pop_str()!
+			v.push(v.alloc_str(base64.encode_str(s)))!
+		}
+		native_base64_decode {
+			s := v.pop_str()!
+			v.push(v.alloc_str(base64.decode_str(s)))!
+		}
+		native_sha256 {
+			s := v.pop_str()!
+			v.push(v.alloc_str(sha256.hexhash(s)))!
+		}
+		native_md5 {
+			s := v.pop_str()!
+			v.push(v.alloc_str(md5.hexhash(s)))!
+		}
+		native_csv_parse {
+			s := v.pop_str()!
+			mut r := csv.new_reader(s)
+			// read() yields one row ([]string) at a time until EOF
+			mut rows := [][]string{}
+			for {
+				row := r.read() or { break }
+				if row.len == 0 {
+					break
+				}
+				rows << row
+			}
+			mut outer := []i64{}
+			for row in rows {
+				mut inner := []i64{}
+				for cell in row {
+					v.strings << cell
+					inner << v.mkstr(v.strings.len - 1)
+				}
+				v.arrays << inner
+				outer << v.mkarr(v.arrays.len - 1)
+			}
+			v.arrays << outer
+			v.push(v.mkarr(v.arrays.len - 1))!
+		}
+		// -------------------------------------------------------------------
+		// extended HTTP: any method, custom headers (a {name: value} struct),
+		// and a per-request timeout in milliseconds
+		native_http_req {
+			timeout_ms := int(v.dec_int(v.pop()!))
+			headers_h := v.pop()!
+			data := v.pop_str()!
+			url := v.pop_str()!
+			method := v.pop_str()!
+			mut h := http.new_header()
+			if v.is_struct(headers_h) && v.valid_struct_handle(headers_h) {
+				for f in v.structs[v.hand(headers_h)].fields {
+					if v.is_str(f.val) && v.valid_handle(f.val) {
+						h.add_custom(f.name, v.strings[v.hand(f.val)]) or {}
+					}
+				}
+			}
+			m := match method.to_upper() {
+				'GET' { http.Method.get }
+				'POST' { http.Method.post }
+				'PUT' { http.Method.put }
+				'DELETE' { http.Method.delete }
+				'PATCH' { http.Method.patch }
+				'HEAD' { http.Method.head }
+				else { return error('http_req: unsupported method "${method}"') }
+			}
+			resp := http.fetch(method: m, url: url, data: data, header: h,
+				read_timeout: i64(timeout_ms) * time.millisecond) or {
+				return error('http_req: ${err.msg()}')
+			}
+			v.push_http_response(resp)!
+		}
+		// -------------------------------------------------------------------
+		// filesystem path helpers
+		native_path_ext {
+			p := v.pop_str()!
+			v.push(v.alloc_str(os.file_ext(p)))!
+		}
+		native_path_abs {
+			p := v.pop_str()!
+			v.push(v.alloc_str(os.abs_path(p)))!
+		}
+		native_path_rel {
+			base := v.pop_str()!
+			p := v.pop_str()!
+			v.push(v.alloc_str(v.rel_path(p, base)))!
+		}
+		// -------------------------------------------------------------------
+		// process spawn with separate stdout/stderr pipes
+		native_exec_full {
+			cmd := v.pop_str()!
+			mut code := 0
+			mut out := ''
+			mut errs := ''
+			if os.user_os() == 'windows' {
+				res := os.execute(cmd)
+				code = res.exit_code
+				out = res.output
+			} else {
+				mut p := os.new_process('sh')
+				p.set_args(['-c', cmd])
+				p.use_stdio_ctl = true
+				p.run()
+				p.wait()
+				if p.err.len > 0 {
+					return error('exec_full: ${p.err}')
+				}
+				code = p.code
+				out = p.stdout_slurp()
+				errs = p.stderr_slurp()
+			}
+			out_h := v.alloc_str(out)
+			err_h := v.alloc_str(errs)
+			mut fields := []Field{len: 3}
+			fields[0] = Field{ name: 'code', val: v.enc_int(i64(code)) }
+			fields[1] = Field{ name: 'stdout', val: out_h }
+			fields[2] = Field{ name: 'stderr', val: err_h }
+			v.structs << StructVal{ fields: fields, by_name: v.index_fields(fields) }
+			v.push(v.mkstruct_handle(v.structs.len - 1))!
+		}
 		else {
 			return error('unknown native builtin ${id}')
 		}
 	}
 }
 
+// rel_path computes a relative path from `base` to `p` (both absolutized),
+// e.g. rel_path("/a/b/c.txt", "/a") == "b/c.txt". Used by os.rel().
+fn (v Vm) rel_path(p string, base string) string {
+	ap := os.abs_path(p).replace('\\', '/')
+	ab := os.abs_path(base).replace('\\', '/')
+	if ap == ab {
+		return '.'
+	}
+	aparts := ap.split('/')
+	bparts := ab.split('/')
+	mut i := 0
+	for i < aparts.len && i < bparts.len && aparts[i] == bparts[i] {
+		i++
+	}
+	mut out := []string{}
+	for _ in i..bparts.len {
+		out << '..'
+	}
+	for j in i..aparts.len {
+		out << aparts[j]
+	}
+	if out.len == 0 {
+		return '.'
+	}
+	return out.join('/')
+}
+
 // push_http_response wraps an HTTP response as a {status, body} struct value
 // so scripts can read res.status and res.body.
 fn (mut v Vm) push_http_response(resp http.Response) ! {
@@ -692,7 +893,7 @@ fn (mut v Vm) push_http_response(resp http.Response) ! {
 	mut fields := []Field{len: 2}
 	fields[0] = Field{ name: 'status', val: v.enc_int(i64(resp.status_code)) }
 	fields[1] = Field{ name: 'body', val: body_h }
-	v.structs << StructVal{ fields: fields }
+	v.structs << StructVal{ fields: fields, by_name: v.index_fields(fields) }
 	v.push(v.mkstruct_handle(v.structs.len - 1))!
 }
 
diff --git a/vm/opcodes.v b/vm/opcodes.v
index e5952e8..ff01edd 100644
--- a/vm/opcodes.v
+++ b/vm/opcodes.v
@@ -150,3 +150,24 @@ const native_now = 170
 const native_time_ms = 171
 const native_format_time = 172
 const native_parse_time = 173
+
+// regex builtins
+const native_regex_match = 174
+const native_regex_find_all = 175
+const native_regex_replace = 176
+const native_regex_split = 177
+
+// crypto/encoding builtins
+const native_base64_encode = 178
+const native_base64_decode = 179
+const native_sha256 = 180
+const native_md5 = 181
+const native_csv_parse = 182
+
+// extended HTTP + filesystem/process builtins
+const native_http_req = 183
+const native_path_ext = 184
+const native_path_abs = 185
+const native_path_rel = 186
+const native_exec_full = 187
+const native_weekday = 188
diff --git a/vm/types.v b/vm/types.v
index 95978d8..830519a 100644
--- a/vm/types.v
+++ b/vm/types.v
@@ -12,14 +12,20 @@ mut:
 	val  i64
 }
 
+// StructVal is a struct (or map) value. `fields` keeps insertion order for
+// rendering and JSON encoding; `by_name` is a hash index for O(1) field
+// lookup by name, so map-style access on large records stays fast.
 struct StructVal {
 mut:
-	fields []Field
+	fields  []Field
+	by_name map[string]int // field name -> index into fields
 }
 
 // Handler records a try/catch handler pushed at runtime.
 struct Closure {
 	entry int // code IP of the function body
+mut:
+	captured []i64 // values of the enclosing locals this closure captures (by value)
 }
 
 struct Handler {
@@ -30,26 +36,27 @@ struct Handler {
 
 struct Vm {
 mut:
-	code      []u8
-	strings   []string
-	arrays    [][]i64
-	structs   []StructVal
-	floats    []f64
-	closures  []Closure
-	stack     []i64
-	sp        int
-	bp        int
-	ip        int
-	trace     bool
-	halted    bool
-	prog_args []string
-	exit_code i64
-	did_exit  bool
-	handlers  []Handler
-	lines     []obj.LineInfo // debug info: code offset -> source line
-	const_strs int          // strings[0..const_strs] are bytecode constants, never collected
-	last_heap  int          // heap size at the last GC check (allocation trigger)
-	build_root string       // directory of the .vrmm build module (build_root() builtin)
+	code       []u8
+	strings    []string
+	arrays     [][]i64
+	structs    []StructVal
+	floats     []f64
+	closures   []Closure
+	stack      []i64
+	sp         int
+	bp         int
+	ip         int
+	trace      bool
+	halted     bool
+	prog_args  []string
+	exit_code  i64
+	did_exit   bool
+	handlers   []Handler
+	lines      []obj.LineInfo // debug info: code offset -> source line
+	fns        []obj.BinFn    // function table (for stack traces)
+	const_strs int            // strings[0..const_strs] are bytecode constants, never collected
+	last_heap  int            // heap size at the last GC check (allocation trigger)
+	build_root string         // directory of the .vrmm build module (build_root() builtin)
 }
 
 fn bool_i64(b bool) i64 {
diff --git a/vm/vm.v b/vm/vm.v
index 56bec0b..4c8e090 100644
--- a/vm/vm.v
+++ b/vm/vm.v
@@ -35,6 +35,7 @@ fn run_internal(bin obj.Bin, entry string, trace bool, args []string, root strin
 		trace:      trace
 		prog_args:  args
 		lines:      bin.lines
+		fns:        bin.fns
 		const_strs: bin.strings.len
 		build_root: root
 	}
@@ -61,7 +62,7 @@ fn run_internal(bin obj.Bin, entry string, trace bool, args []string, root strin
 	v.bp = v.sp
 	v.ip = entry_ip
 	v.exec() or {
-		return error('${err.msg()} at ${v.where()}')
+		return error('${err.msg()} at ${v.where()}\n${v.stack_trace()}')
 	}
 	if v.did_exit {
 		return v.exit_code
@@ -75,14 +76,57 @@ fn run_internal(bin obj.Bin, entry string, trace bool, args []string, root strin
 // where returns a source-level location for the current instruction pointer:
 // `line 12 (ip 345)` when debug info is available, otherwise just `(ip 345)`.
 fn (v Vm) where() string {
+	return 'line ${v.line_at(v.ip)} (ip ${v.ip})'
+}
+
+// line_at maps a code offset to its source line via the line table.
+fn (v Vm) line_at(ip int) int {
 	// line table entries are recorded in code order, so walk backwards from
-	// the most recent entry to find the last one at or before v.ip
+	// the most recent entry to find the last one at or before ip
 	for i := v.lines.len - 1; i >= 0; i-- {
-		if v.ip >= int(v.lines[i].off) {
-			return 'line ${v.lines[i].line} (ip ${v.ip})'
+		if ip >= int(v.lines[i].off) {
+			return v.lines[i].line
 		}
 	}
-	return '(ip ${v.ip})'
+	return 0
+}
+
+// func_at returns the name of the function whose body contains the given
+// code offset. Functions are laid out sequentially, so the enclosing
+// function is the one with the greatest entry point <= ip.
+fn (v Vm) func_at(ip int) string {
+	mut name := '?'
+	for f in v.fns {
+		if f.entry <= ip {
+			name = f.name
+		}
+	}
+	return name
+}
+
+// stack_trace renders the call chain at the moment an error is raised, from
+// the innermost frame out to main. Each frame's return address and saved bp
+// live in the frame header pushed by `call`: [retaddr, old_bp, argc] at
+// bp-3..bp-1. The synthetic entry frame has retaddr == -1 (the halt sentinel).
+fn (mut v Vm) stack_trace() string {
+	mut out := []string{}
+	mut bp := v.bp
+	mut ip := v.ip
+	mut guard := 0
+	// note: sp may have dropped below bp (an error handler pops values), so
+	// the frame chain is bounded by the guard and the old_bp < bp invariant
+	for bp >= 3 && guard < 10000 {
+		out << '  at ${v.func_at(ip)} (line ${v.line_at(ip)})'
+		ret := v.dec_int(v.stack[bp - 3])
+		old_bp := int(v.dec_int(v.stack[bp - 2]))
+		if ret == -1 || old_bp < 0 || old_bp >= bp {
+			break // reached the synthetic entry frame
+		}
+		ip = int(ret)
+		bp = old_bp
+		guard++
+	}
+	return out.join('\n')
 }
 
 fn (mut v Vm) exec() ! {
@@ -303,37 +347,67 @@ fn (mut v Vm) exec() ! {
 			}
 			op_aget {
 				v.ip++
-				idx := int(v.dec_int(v.pop()!))
+				idxv := v.pop()!
 				h := v.pop()!
-				if v.is_arr(h) && v.valid_arr_handle(h) {
-					a := v.arrays[v.hand(h)]
-					if idx < 0 || idx >= a.len {
-						return error('array index ${idx} out of bounds (len ${a.len})')
+				// dynamic map read: m[key_expr] where the base is a struct and the
+				// index evaluates to a string
+				if v.is_struct(h) && v.valid_struct_handle(h) && v.is_str(idxv) && v.valid_handle(idxv) {
+					fname := v.strings[v.hand(idxv)]
+					s := v.structs[v.hand(h)]
+					idx, ok := v.field_idx(s, fname)
+					if ok {
+						v.push(s.fields[idx].val)!
+					} else {
+						return error('no field "${fname}" on struct')
 					}
-					v.push(a[idx])!
-				} else if v.is_str(h) && v.valid_handle(h) {
-					// rune-based string indexing: s[i] is the i-th character
-					runes := v.strings[v.hand(h)].runes()
-					if idx < 0 || idx >= runes.len {
-						return error('string index ${idx} out of bounds (len ${runes.len})')
-					}
-					v.push(v.alloc_str(runes[idx].str()))!
 				} else {
-					return error('indexing a non-array, non-string value')
+					idx := int(v.dec_int(idxv))
+					if v.is_arr(h) && v.valid_arr_handle(h) {
+						a := v.arrays[v.hand(h)]
+						if idx < 0 || idx >= a.len {
+							return error('array index ${idx} out of bounds (len ${a.len})')
+						}
+						v.push(a[idx])!
+					} else if v.is_str(h) && v.valid_handle(h) {
+						// rune-based string indexing: s[i] is the i-th character
+						runes := v.strings[v.hand(h)].runes()
+						if idx < 0 || idx >= runes.len {
+							return error('string index ${idx} out of bounds (len ${runes.len})')
+						}
+						v.push(v.alloc_str(runes[idx].str()))!
+					} else {
+						return error('indexing a non-array, non-string value')
+					}
 				}
 			}
 			op_aset {
 				v.ip++
 				val := v.pop()!
-				idx := int(v.dec_int(v.pop()!))
+				idxv := v.pop()!
 				h := v.pop()!
-				if !v.is_arr(h) || !v.valid_arr_handle(h) {
-					return error('indexing a non-array value')
+				// dynamic map write: m[key_expr] = v (string key on a struct)
+				if v.is_struct(h) && v.valid_struct_handle(h) && v.is_str(idxv) && v.valid_handle(idxv) {
+					fname := v.strings[v.hand(idxv)]
+					mut s := v.structs[v.hand(h)]
+					idx, ok := v.field_idx(s, fname)
+					if ok {
+						s.fields[idx].val = val
+					} else {
+						// setting a missing field adds it, so maps can grow
+						s.fields << Field{ name: fname, val: val }
+						s.by_name[fname] = s.fields.len - 1
+					}
+					v.structs[v.hand(h)] = s
+				} else {
+					idx := int(v.dec_int(idxv))
+					if !v.is_arr(h) || !v.valid_arr_handle(h) {
+						return error('indexing a non-array value')
+					}
+					if idx < 0 || idx >= v.arrays[v.hand(h)].len {
+						return error('array index ${idx} out of bounds (len ${v.arrays[v.hand(h)].len})')
+					}
+					v.arrays[v.hand(h)][idx] = val
 				}
-				if idx < 0 || idx >= v.arrays[v.hand(h)].len {
-					return error('array index ${idx} out of bounds (len ${v.arrays[v.hand(h)].len})')
-				}
-				v.arrays[v.hand(h)][idx] = val
 			}
 			op_alen {
 				v.ip++
@@ -371,7 +445,7 @@ fn (mut v Vm) exec() ! {
 					}
 					fields[i] = Field{ name: v.strings[v.hand(name)], val: val }
 				}
-				v.structs << StructVal{ fields: fields }
+				v.structs << StructVal{ fields: fields, by_name: v.index_fields(fields) }
 				v.push(v.mkstruct_handle(v.structs.len - 1))!
 			}
 			op_sget {
@@ -385,15 +459,11 @@ fn (mut v Vm) exec() ! {
 					return error('internal: field name is not a string')
 				}
 				fname := v.strings[v.hand(name)]
-				mut found := false
-				for f in v.structs[v.hand(h)].fields {
-					if f.name == fname {
-						v.push(f.val)!
-						found = true
-						break
-					}
-				}
-				if !found {
+				s := v.structs[v.hand(h)]
+				idx, ok := v.field_idx(s, fname)
+				if ok {
+					v.push(s.fields[idx].val)!
+				} else {
 					return error('no field "${fname}" on struct')
 				}
 			}
@@ -411,18 +481,14 @@ fn (mut v Vm) exec() ! {
 				}
 				fname := v.strings[v.hand(name)]
 				mut s := v.structs[v.hand(h)]
-				mut found := false
-				for i, f in s.fields {
-					if f.name == fname {
-						s.fields[i].val = val
-						found = true
-						break
-					}
-				}
-				if !found {
+				idx, ok := v.field_idx(s, fname)
+				if ok {
+					s.fields[idx].val = val
+				} else {
 					// setting a missing field adds it, so records can be built
 					// incrementally from an empty `{}`
 					s.fields << Field{ name: fname, val: val }
+					s.by_name[fname] = s.fields.len - 1
 				}
 				v.structs[v.hand(h)] = s
 			}
@@ -526,7 +592,14 @@ fn (mut v Vm) exec() ! {
 			op_closure {
 				v.ip++
 				entry := int(v.read_i64())
-				v.closures << Closure{ entry: entry }
+				n := int(v.read_i64())
+				// the captured values were pushed by the compiler in capture
+				// order; pop them back into the closure's own array
+				mut captured := []i64{len: n}
+				for i := n - 1; i >= 0; i-- {
+					captured[i] = v.pop()!
+				}
+				v.closures << Closure{ entry: entry, captured: captured }
 				v.push(v.mkclosure(v.closures.len - 1))!
 			}
 			op_call_closure {
@@ -537,17 +610,30 @@ fn (mut v Vm) exec() ! {
 				if !v.is_closure(h) || !v.valid_closure_handle(h) {
 					return error('cannot call a non-function value')
 				}
-				entry := v.closures[v.hand(h)].entry
-				// Shift args left to overwrite the closure slot (and drop the
-				// duplicated tail), so the callee's retv lands exactly where the
-				// call sequence began and no stale value is left below the
-				// result. The caller's own local holding the closure sits below
-				// the pushed sequence and is never touched.
-				for i := 0; i < argc; i++ {
-					v.stack[v.sp - argc - 1 + i] = v.stack[v.sp - argc + i]
+				cl := v.closures[v.hand(h)]
+				n := cl.captured.len
+				c := v.sp - argc - 1 // closure slot
+				// Rearrange the stack from [...closure, arg_0..arg_{argc-1}] to
+				// [capture_0..capture_{n-1}, arg_0..arg_{argc-1}]: the captures
+				// take over the closure slot, and the args shift by (1 - n) so
+				// the callee sees captures as its leading locals followed by the
+				// real arguments. v.call cleans the whole region up on ret.
+				if n > 1 {
+					// shifting right: copy backwards to avoid clobbering
+					for i := argc - 1; i >= 0; i-- {
+						v.stack[c + n + i] = v.stack[c + 1 + i]
+					}
+				} else {
+					// shifting left (or no shift): copy forwards
+					for i := 0; i < argc; i++ {
+						v.stack[c + n + i] = v.stack[c + 1 + i]
+					}
 				}
-				v.sp-- // drop the duplicated arg tail; closure slot was consumed
-				v.call(entry, argc)
+				for i in 0..n {
+					v.stack[c + i] = cl.captured[i]
+				}
+				v.sp = c + n + argc
+				v.call(cl.entry, argc + n)
 			}
 			op_argc {
 				v.ip++
@@ -595,6 +681,25 @@ fn (mut v Vm) exec() ! {
 	}
 }
 
+// field_idx returns the index of a named field via the hash index, or
+// (0, false) when the field does not exist.
+fn (v Vm) field_idx(s StructVal, fname string) (int, bool) {
+	if fname in s.by_name {
+		return s.by_name[fname], true
+	}
+	return 0, false
+}
+
+// index_fields builds the name -> index hash map for a freshly built field
+// list (used by mkstruct and other struct constructors).
+fn (v Vm) index_fields(fields []Field) map[string]int {
+	mut m := map[string]int{}
+	for i, f in fields {
+		m[f.name] = i
+	}
+	return m
+}
+
 // op_shas checks if a struct has a field with the given name.
 // stack: struct, "key"  →  pushes 1 if found, 0 if not.
 fn (mut v Vm) op_shas() ! {
@@ -608,13 +713,7 @@ fn (mut v Vm) op_shas() ! {
 		return error('internal: field name is not a string')
 	}
 	fname := v.strings[v.hand(name)]
-	mut found := false
-	for f in v.structs[v.hand(h)].fields {
-		if f.name == fname {
-			found = true
-			break
-		}
-	}
+	found := fname in v.structs[v.hand(h)].by_name
 	v.push(v.enc_int(if found { 1 } else { 0 }))!
 }
 
@@ -629,19 +728,22 @@ fn (mut v Vm) op_sdel() ! {
 	}
 	if !v.is_str(name) || !v.valid_handle(name) {
 		return error('internal: field name is not a string')
-	}
-	fname := v.strings[v.hand(name)]
-	mut s := v.structs[v.hand(h)]
-	mut new_fields := []Field{}
-	for f in s.fields {
-		if f.name != fname {
-			new_fields << f
+	}		fname := v.strings[v.hand(name)]
+		mut s := v.structs[v.hand(h)]
+		idx, ok := v.field_idx(s, fname)
+		if ok {
+			mut new_fields := []Field{}
+			for i, f in s.fields {
+				if i != idx {
+					new_fields << f
+				}
+			}
+			s.fields = new_fields
+			s.by_name = v.index_fields(new_fields)
+			v.structs[v.hand(h)] = s
 		}
+		v.push(h)!
 	}
-	s.fields = new_fields
-	v.structs[v.hand(h)] = s
-	v.push(h)!
-}
 
 // op_slen returns the number of fields in a struct.
 // stack: struct  →  pushes field count.