Conditionals in Sesi

Sesi uses if and else for branching. The condition is any expression that evaluates to a truthy or falsy value — no parentheses required.

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Basic if

if_stmt := 'if' expression block ('else' block)?

let score = 87

if score >= 90 {
  show "excellent"
}

The block only runs when the condition is truthy. If the condition is false and there is no else, execution continues after the block.

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if / else

let ready = false

if ready {
  show "starting"
} else {
  show "not ready yet"
}

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else if Chains

Chain additional conditions with else if. Sesi evaluates each branch top to bottom and runs the first one that matches:

let score = 72

if score >= 90 {
  show "excellent"
} else if score >= 70 {
  show "passing"
} else if score >= 50 {
  show "marginal"
} else {
  show "needs work"
}

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Truthy & Falsy Values

Sesi follows straightforward truthiness rules:

This means you can test for the presence of a value directly — no != null required:

let title = args[0]   // may be null if no arg passed

if title {
  show "Title:" title
} else {
  show "No title provided"
}

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Comparison Operators

let x = 10

if x == 10  { show "ten" }
if x != 0   { show "non-zero" }
if x >= 5   { show "at least five" }

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Logical Operators

Combine conditions with && (and), || (or), and ! (not). Both && and || short-circuit.

let age = 25
let paid = true

if age >= 18 && paid {
  show "access granted"
}

if age < 13 || !paid {
  show "access denied"
}

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One-liner Blocks

Block braces can be condensed onto a single line:

if ready { show "go" }
if !ready { show "wait" }

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Conditionals Inside Functions

if/else is commonly used inside fn blocks to control what gets returned:

fn classify(score: number) -> string {
  if score >= 90 { return "excellent" }
  if score >= 70 { return "passing" }
  return "needs work"
}

show classify(95)   // excellent
show classify(74)   // passing
show classify(40)   // needs work

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Quick Reference

// Basic if
if x > 0 { show "positive" }

// if / else
if active { show "on" } else { show "off" }

// else if chain
if score >= 90 {
  show "A"
} else if score >= 70 {
  show "B"
} else {
  show "C"
}

// Truthiness check
if value { show "has value" }

// Logical operators
if a > 0 && b > 0 { show "both positive" }
if a == 0 || b == 0 { show "at least one is zero" }
if !flag { show "flag is off" }

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