Control flow

Braces are always required. if is an expression. loop can return a value. Loops can be labeled for nested breaks.

if / elif / else

scratch.xs

let x = 5

if x > 0 {
  println("positive")
} elif x < 0 {
  println("negative")
} else {
  println("zero")
}

-- if as an expression
let sign = if x > 0 { "+" } else if x < 0 { "-" } else { "0" }
println(sign)

while

scratch.xs

var i = 0
while i < 5 {
  print("{i} ")
  i += 1
}
println()

for

for iterates over arrays, ranges, strings (via .chars()), maps, and any generator.

scratch.xs

-- over array
for x in [10, 20, 30] {
  print("{x} ")
}
println()

-- over range (exclusive)
for i in 0..5 {
  print("{i} ")
}
println()

-- over range (inclusive)
for i in 1..=3 {
  print("{i} ")
}
println()

scratch.xs

-- over map: iterates key-value pairs
let m = #{"a": 1, "b": 2, "c": 3}
for (k, v) in m {
  println("{k} = {v}")
}

loop

loop runs forever until an explicit break. It can return a value via break.

scratch.xs

var n = 0
let result = loop {
  n += 1
  if n >= 5 { break n * 10 }
}
println(result)      -- 50

break and continue

scratch.xs

for i in 0..10 {
  if i % 2 == 0 { continue }   -- skip even
  if i > 7 { break }            -- stop early
  print("{i} ")
}
println()                       -- 1 3 5 7

Labeled loops

Labels let you break or continue an outer loop from inside a nested one.

scratch.xs

var found = false
outer: for i in 0..5 {
  for j in 0..5 {
    if i * j == 6 {
      println("found: i={i}, j={j}")
      found = true
      break outer
    }
  }
}
println(found)       -- true

Edit this page on GitHub ->