NAME

Syntax::Operator::In - placeholder module for infix element-of-list meta-operator

DESCRIPTION

This empty module is a placeholder for eventually implementing syntax for a generic element-of-list meta-operator, perhaps using syntax such as the following:

   use Syntax::Operator::In;

   if($x in<eq> @some_strings) {
      say "x is one of the given strings";
   }

It is currently empty, because the underlying syntax parsing module, XS::Parse::Infix, does not yet support the additional syntax required to parameterize this meta-operator.

Instead, for operators that already specialize on string or numerical equality, see instead Syntax::Operator::Elem.

TODO

• Improve runtime performance of compiletime-constant sets of strings, by detecting when the RHS contains string constants and convert it into a hash lookup.

• The real in meta-operator. This first requires more extensive parsing support from XS::Parse::Infix.

• Consider cross-module integration with Syntax::Keyword::Match, permitting

     match($val : elem) {
        case(@arr_of_strings) { ... }
     }

  Or perhaps this would be too weird, and maybe match/case should have an "any-of" list/array matching ability itself. See also https://rt.cpan.org/Ticket/Display.html?id=143482.

AUTHOR

Paul Evans <leonerd@leonerd.org.uk>