Duration Literals

The Duration and Instant types have specialized literal support.

Syntax#

Duration literals are written as a decimal integer or decimal float immediately followed by a unit suffix:

• Examples:
• 10ns
• 250us
• 5ms
• 1s
• 1.5s
• 2min
• 1h

The unit suffix is part of the literal token; the lexer must not split it into an integer token followed by an identifier.

Units#

Recognized suffixes:

• ns — nanoseconds
• us — microseconds
• ms — milliseconds
• s — seconds
• min — minutes
• h — hours
• d — days

Semantics#

Duration literals evaluate to a Duration value represented as an i64 nanosecond count.

• For integer forms (e.g. 5ms), the value is scaled exactly.
• For floating-point forms (e.g. 1.5s), the value is scaled and then rounded toward zero to an integral nanosecond count.

If the scaled value does not fit in i64, compilation fails.

Compiler requirements:

• Implement lexing rules that distinguish unit suffixes from identifiers.
• Map duration literals to the Duration type with correct unit scaling.
• Ensure constant-evaluation behavior (rounding, overflow) matches the spec.