NAME

FP::Pure - base class for all purely functional data structure

SYNOPSIS

UNIVERSAL::isa ($v, "FP::Pure") # true if $v is a purely functional DS

# but usually:
use FP::Predicates;
is_pure ($v) # true if $v is (officially) immutable, detectable from
             # inheritance of FP::Pure or other means

DESCRIPTION

Base class for all data structures that don't allow mutation (by ordinary programs), i.e. are persistent (1).

(1) as in https://en.wikipedia.org/wiki/Persistent_data_structure

More precisely, those objects that don't have methods that when called make other methods non-functions.