Rules / Operators / symbolic unary

^ Skeleton

prefix ^

^
prefixsymbolic unary 5/27left-assocRaku++ runs this — 6 of 6 results differdocs.raku.org ↗

The rules for ^ have not been written yet. Everything below is extracted rather than authored: the official documentation supplies the classification, and the interpreters were asked directly about the rest.

What is established #

Classification #

^ is parsed as a prefix at the symbolic unary precedence level, left-associative.

That is level 5 of 27 on the ladder, counting from the tightest. Operators sharing a level bind equally; grouping among them is decided by associativity alone.

Shares its precedence level with #

?, !, //, +, -, ~, |, +^, ~^, ?^.

These all bind equally tightly, so an expression mixing them groups by associativity alone.

What the interpreter said #

Raku++ parses this spelling. Asked to compile:

my $a = 6; sink(^ $a)

…it got through the parser. On its own that establishes very little: it says nothing about whether the construct executes, let alone whether the result is right. Where the behaviour table below exists, that is the stronger evidence — those expressions were actually run.

Covered upstream #

The official documentation has a section for this construct: docs.raku.org. Until the rules here are written, that is the better reference.

Observed behaviour #

Each expression below was executed by both interpreters when this page was built; the results are recorded, not written. The operands are chosen to cross the boundaries that catch people out: string against number, a list where a scalar was meant, a boolean, an undefined value, and an exact rational.

6 of 6 of these disagree between Raku++ and Rakudo — shown side by side below. A disagreement here is a defect report waiting to be written, not a documented rule.

ExpressionRaku++Rakudo
^ (1)Range | 0..^1Range | ^1
^ ("a")Range | 0..^0ERR Cannot convert string to number: base-10 number must begin with valid digits or '.' in '<HERE>a' (indicated by <HERE>)
^ ((1, 2))Range | 0..^2Range | ^2
^ (True)Range | 0..^1Range | ^True
^ (Nil)Range | 0..^0Range | ^0
^ (1/2)Range | 0..^0Range | 0..^0.5