Types

Type Conversions

Implicit Conversions

• int → float (in mixed arithmetic)
• character literal → int (in binary operations with an integer operand, coerced to Unicode codepoint value)

Explicit Conversions (using as operator)

Only safe (widening) casts are allowed. The compiler rejects casts that could lose data.

Cast targets MUST be either a named ranged typealias (for int, float, or byte) or the bare keyword bool. Bare int/float/byte as cast targets are rejected — every primitive cast must travel through a typealias so the range-narrowing intent is explicit.

typealias Octet = byte(0 to u8.max)
typealias Tally = int(0 to i64.max)
typealias Real = float(f64.min to f64.max)

var b = 42 as Octet        // int literal 0-255 to byte (OK)
var i = b as Tally         // byte to int (OK)
var f = b as Real          // byte to float (OK)
var g = 100 as Real        // int to float (OK)

Supported casts:

• byte → int (widening)
• byte → float (widening)
• int → float (widening)
• int literal 0-255 → byte (compile-time range-checked)

Casts to or from bool are not allowed. Narrowing casts (int variable → byte, float → int, float → byte) are not allowed. Attempting an unsupported cast produces error E3009.

A cast whose target alias already covers the source alias’s full range — for example let x Integer = ...; let y = x as Integer — is rejected with E3010 “unneeded cast”. The compiler auto-widens at use sites, so any explicit cast must actually narrow or refine. Bare-literal sources (42 as Byte) are exempt because the literal has no source alias to compare against.

Converting floats to integers: The float → int cast is not supported because it silently truncates. Use explicit functions instead to make your intent clear:

• trunc(x) - Truncate toward zero (removes fractional part)
• round(x) - Round to nearest integer
• floor(x) - Round down to nearest integer
• ceil(x) - Round up to nearest integer

Example:

var f = 3.7
var i1 = trunc(f)  // 3 (toward zero)
var i2 = round(f)  // 4 (nearest)
var i3 = floor(f)  // 3 (down)
var i4 = ceil(f)   // 4 (up)