Loops

examples/arrays.vr

@@ -0,0 +1,73 @@
+// arrays.vr — arrays and for loops.
+// Run with:  vr run examples/arrays.vr
+
+fn sum(items) {
+	let total = 0
+	for x in items {
+		total = total + x
+	}
+	return total
+}
+
+fn main() {
+	// array literal
+	let a = [10, 20, 30]
+	println(a)              // [10, 20, 30]
+	println(len(a))         // 3
+
+	// indexing: read and write
+	println(a[0])           // 10
+	a[1] = 99
+	println(a)              // [10, 99, 30]
+
+	// growing with push (mutates in place)
+	push(a, 40)
+	println(a)              // [10, 99, 30, 40]
+	println(len(a))         // 4
+
+	// iterate the array
+	let total = sum(a)
+	println("sum = ")
+	println(total)          // 179
+
+	// range for loops
+	for i in 0..5 {
+		println("i = " + i) // 0 1 2 3 4
+	}
+
+	for n in 1...3 {
+		println("n = " + n) // 1 2 3 (inclusive)
+	}
+
+	// nested loops
+	let grid = [[1, 2], [3, 4]]
+	for row in grid {
+		for cell in row {
+			print(cell)
+			print(" ")
+		}
+		println("")
+	}
+	println(grid[1][0])     // 3
+
+	// build an array in a loop
+	let squares = []
+	for i in 0..5 {
+		push(squares, i * i)
+	}
+	println(squares)        // [0, 1, 4, 9, 16]
+
+	// loop variables are scoped to the loop
+	let i = 100
+	for i in 0..3 {
+		println(i)
+	}
+	println("i is back to ")
+	println(i)              // 100
+
+	assert sum([1, 2, 3, 4]) == 10
+	assert len(squares) == 5
+	assert squares[4] == 16
+	assert a == a            // arrays compare by identity
+	println("all array asserts passed")
+}

examples/tests.vr

@@ -35,6 +35,49 @@ fn test_booleans() {
 	assert not (x == 0)
 }
 
+fn test_arrays() {
+	let a = [1, 2, 3]
+	assert len(a) == 3
+	assert a[0] == 1
+	assert a[2] == 3
+	a[1] = 42
+	assert a[1] == 42
+	push(a, 4)
+	assert len(a) == 4
+	assert a[3] == 4
+	let m = [[1, 2], [3, 4]]
+	assert m[1][0] == 3
+}
+
+fn test_for_range() {
+	let total = 0
+	for i in 0..5 {
+		total = total + i
+	}
+	assert total == 10 // 0+1+2+3+4
+	let inc = 0
+	for i in 1...3 {
+		inc = inc + i
+	}
+	assert inc == 6 // 1+2+3 (inclusive)
+}
+
+fn test_for_in() {
+	let a = [5, 6, 7]
+	let total = 0
+	for x in a {
+		total = total + x
+	}
+	assert total == 18
+	let squares = []
+	for i in 0..4 {
+		push(squares, i * i)
+	}
+	assert squares == squares // identity comparison
+	assert len(squares) == 4
+	assert squares[3] == 9
+}
+
 fn test_failing() {
 	// this one is meant to fail — shows up in `vr test` output
 	assert 1 == 2