Definedness Constraints Smiley

Definedness constraints A container can also enforce a variable to be defined. Put a smiley in the declaration: my Int:D $def = 3; say $def; # OUTPUT: «3» $def = Int; # Typecheck failure

A programming tutorial screenshot demonstrates a definedness constraint in Raku, where a variable declared as Int:D must contain a defined integer. The joke is the cheerful-looking smiley-like colon in the declaration contrasted with the typecheck failure when assigning the undefined type object Int.

• @rzeczyzabawne / 12700 2023-10-13