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var

Translation status: English reader-locale proof. Term names and code fences follow the en pack; supporting prose may still be English.

Declares a mutable binding.

Aliases: let, mutable

Syntax: var <type|_> <pattern> [← <expression>]

Category#

binding

Examples#

radix/corpus/varia/varia.fab (canonical · keyword)#

Declares a mutable binding.

# =============================================================================
# var — Declares a mutable binding.
# =============================================================================
#
# What this teaches:
#   • Mutable bindings — `var` for values that can be reassigned after declaration
#   • Immutable bindings — `const` and `let` for values that cannot be reassigned
#
# Common mistakes:
#   • declaring var when the binding is never reassigned — use const instead (WARN013)
#
# See also: const, ←, ↑
# =============================================================================




# Mutable and immutable variable declarations
#
# var <name> ← <expr>   -- mutable binding (may reassign)
# const <name> ← <expr>   -- immutable binding (see const/fixum.fab)
#
# GRAMMAR:
#   bindingStmt :← ('var' | 'const') type? ident '←' expr
#
# EXPECTED OUTPUT:
#   0, 1, 11, "Salve, Mundus!", 30, "Vale"

main {
    # --- Mutable bindings with var ---

    var _ computus ← 0
    print computus

    computus ← 1
    print computus

    computus ← computus + 10
    print computus

    # --- Immutable bindings: const _ and let ---

    const _ salutatio ← "Salve, Mundus!"
    print salutatio

    # let compresses repeated const _ when chaining inferred locals
    let x ← 10
    let y ← 20
    let sum ← x + y
    print sum

    # --- Reassign only var bindings ---

    var _ nuntius ← "Salve"
    nuntius ← "Vale"
    print nuntius
}

Expected output:

0
1
11
Salve, Mundus!
30
Vale