Terms with named arguments (static dicts)

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In this PIP we deal with terms with named arguments, a.k.a. static dicts. See PIP 0102 for the PIP for dynamic dics.

Static dictionaries

Proposal: tag{k1:v1, ..., kn:vn} maps to tag(v1, ..., vn) based on e.g. argnames.

Existing practice

ECLiPSe

See https://www.cs.nmsu.edu/~ipivkina/ECLIPSE/doc/applications.pdf https://www.eclipseclp.org/doc/bips/kernel/syntax/struct-1.html

Called “Named structures”

Declaration:

:- [local/export] struct(tag(k1, ..., kn)).

Usage:

  • tag{k1:v1, ..., kn:vn} expands to tag(v1,...,vn)
  • k_i of tag expands to i
  • property(arity) of tag expands to n
  • property(functor) of tag expands to tag
  • subscript syntax Term[arg1 of tag]
arg(arg1 of tag, Term, Arg)
Term[arg1 of tag]

Ciao

See https://ciao-lang.org/ciao/build/doc/ciao.html/argnames_doc.html

Declaration:

:- argnames tag(k1, ..., kn).

Usage:

  • tag${k1=>V1,...,kn=>Vn} expands to tag(V1,...,Vn), values for missing keys are unbound.
  • tag${/} expands to tag/N
  • tag${argnames} expands to list of keys ([k1,...,kn])
  • (expanded as goal) tag${...,K=>V,...} with variables in keys are expanded to runtime lookups (similar to like get_dict/3)
  • (expanded as goal) $~(T, tag${..., k=>V, ...}, NewT) replace values of specific tags

SWI-Prolog (no dicts of this type)

See https://www.swi-prolog.org/pldoc/man?section=record

Declaration:

:- record tag(arg1[:type1[=default]], arg2, ...)

Access:

tag_arg1(Term, Arg)

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