Control Flow

If/Else

if condition {
  // then branch
}

if condition {
  // then
} else {
  // else
}

if x < 0 {
  print("negative")
} else if x == 0 {
  print("zero")
} else {
  print("positive")
}

let count = 5

// This works
if count > 0 {
  print("has items")
}

// This does NOT work
// if count { ... }  // Error: condition must be boolean

For-In Loop

Iterate over arrays:

let items = ["apple", "banana", "cherry"]

for item in items {
  print(item)
}

Iterate over ranges:

// 1 to 5 inclusive
for i in 1..5 {
  print(i)  // 1, 2, 3, 4, 5
}

Loop Context Modifiers

Control how AI context is managed in loops. The modifier goes after the closing brace:

// Default: keep full history
for item in items {
  do "Process {item}"
}

// Forget: clear AI context each iteration
for item in items {
  do "Process {item}"
} forget

// Compress: summarize context to save tokens
for item in items {
  do "Process {item}"
} compress

// Verbose: explicitly keep full history (default)
for item in items {
  do "Process {item}"
} verbose

See Context Management for more details.

While Loop

let count = 0

while count < 10 {
  print(count)
  count = count + 1
}

Break

The break statement exits the innermost loop immediately:

for i in [1, 2, 3, 4, 5] {
  if i == 3 {
    break
  }
  print(i)  // prints 1, 2
}

Works in both for-in and while loops:

let i = 0
while i < 100 {
  i = i + 1
  if i == 5 {
    break
  }
}
// i is now 5

Nested Loops

break only exits the innermost loop:

for i in [1, 2, 3] {
  for j in [1, 2, 3, 4, 5] {
    if j == 2 {
      break  // only exits inner loop
    }
    print(j)  // prints 1 for each outer iteration
  }
  print("outer")  // still runs 3 times
}

Combining with AI

Loops are powerful when combined with AI expressions:

let topics = ["AI", "Climate", "Space"]
let summaries: text[] = []

for topic in topics {
  let summary = do "Write a one-sentence summary about {topic}"
  summaries.push(summary)
}

Use forget when processing many items to avoid context overflow:

for article in articles {
  let analysis = do "Analyze this article: {article}"
  results.push(analysis)
} forget