Loops in Kiwi

Kiwi provides three main looping constructs: repeat, while, and for. All loops support break (exit early) and next (skip to next iteration).

Quick Reference

Construct	Use case	Iterator var?	Index available?	Infinite possible?
repeat n	Known number of repetitions	Yes (via as)	Yes	No
while	Condition-based (including infinite)	No	Manual	Yes
for … in …	Collection / range / generator	Yes	Yes (optional)	Yes (generators)

1. repeat – Fixed number of iterations

Simplest loop: run a block exactly n times (n must be a positive integer).

Basic syntax

repeat 5 do
  println "Hello"
end
# prints "Hello" five times

With iterator variable (as)

The iterator starts at 1 and goes up to n.

sum = 0

repeat 10 as i do
  sum += i
end

println sum          # 55   (1+2+...+10)

Note: repeat 0 is a no-op (does nothing).

2. while – Condition-based loop

Runs as long as the condition is true.

Basic syntax

count = 1

while count <= 5 do
  println count
  count += 1
end
# 1 2 3 4 5

Infinite loop

while true do
  print "\rWaiting... (Ctrl+C to exit)"
  task::sleep(400)
end

Early exit with break

i = 0
while true do
  i += 1
  println i

  break when i >= 7   # clean guard style
end
# prints 1 through 7

Skip iteration with next

i = 0
while i < 10 do
  i += 1

  next when i % 2 == 0   # skip even numbers

  println i              # only odd numbers
end
# 1 3 5 7 9

3. for – Iteration over collections, ranges & generators

Most common loop in Kiwi — used for lists, hashmaps, ranges, and generators.

Syntax

for item in collection do
  # ...
end

# With index
for item, idx in collection do
  # idx starts at 0
end

# With key-value (hashmaps)
for key, value in hashmap do
  # ...
end

Examples

Lists

fruits = ["apple", "banana", "cherry"]

for fruit in fruits do
  println fruit
end
# apple
# banana
# cherry

# With index
for fruit, i in fruits do
  println "${i + 1}. ${fruit}"
end
# 1. apple
# 2. banana
# 3. cherry

Ranges

for i in [1 to 5] do         # 1,2,3,4,5
  println i
end

for i in [10 to 1] do        # countdown
  print "${i} "
end
# 10 9 8 7 6 5 4 3 2 1

Hashmaps

scores = { alice: 95, bob: 82, carol: 100 }

# key-value pairs
for name, score in scores do
  println "${name}: ${score}"
end

# only keys
for name in scores.keys() do
  println name
end

# only values
for score in scores.values() do
  println score
end

Early exit & skipping in for

for num in [1 to 20] do
  next when num % 3 == 0     # skip multiples of 3
  break when num > 15        # stop early

  println num
end
# 1 2 4 5 7 8 10 11 13 14

Best practices & tips

• Prefer for when iterating collections or known ranges — it's the most idiomatic.
• Use while true + break when … for clean infinite/event loops.
• repeat is great for simple fixed-count tasks or generating sequences.
• Guard clauses (break when, next when) reduce nesting and improve readability.
• Avoid mutating the collection inside a for loop over it (use indices or .clone() if needed).

See also: - Ranges - Lists - Hashmaps - Generators - Control Flow – when guards