The standard library string_chartype package implements C-style predicates on characters in strings. This is modelled after the Unix C libraries. Each predicate comes in two forms; one that works on integers, and one that works on an arbitrary character in a string. The meanings of these predicates are documented in Section 3 of the Unix manual.
The string_chartype package implements the String_Chartype API.
The string_chartype package source code is in src/lib/std/src/string-chartype.pkg.
See also: Int_Chartype. The above information is manually maintained and may contain errors.