remove vestigial prolog/ directory (#444)

2020-06-12 18:26:38 -06:00
parent 5ffb4597b3
commit 33325f1574
89 changed files with 327 additions and 298 deletions
--- a/src/lib/error.pl
+++ b/src/lib/error.pl
@@ -0,0 +1,112 @@
+:- module(error, [must_be/2,
+                  can_be/2,
+                  instantiation_error/1,
+                  domain_error/3,
+                  type_error/3
+                  ]).
+
+/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+   Written September 2018 by Markus Triska (triska@metalevel.at)
+   I place this code in the public domain. Use it in any way you want.
+- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
+
+
+/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+   must_be(Type, Term)
+
+   This predicate is intended for type-checks of built-in predicates.
+
+   It asserts that Term is:
+
+       1) instantiated *and*
+       2) instantiated to an instance of the given Type.
+
+   It corresponds to usage mode +Term.
+
+   Currently, the following types are supported:
+
+       - integer
+       - atom
+       - list
+       - boolean
+- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
+
+must_be(Type, Term) :-
+        must_be_(type, Type),
+        must_be_(Type, Term).
+
+must_be_(Type, _) :-
+        var(Type),
+        instantiation_error(must_be/2).
+must_be_(var, Term) :-
+        (   var(Term) -> true
+        ;   throw(error(uninstantiation_error, must_be/2))
+        ).
+must_be_(integer, Term) :- check_(integer, integer, Term).
+must_be_(atom, Term)    :- check_(atom, atom, Term).
+must_be_(list, Term)    :- check_(ilist, list, Term).
+must_be_(type, Term)    :- check_(type, type, Term).
+must_be_(boolean, Term) :- check_(boolean, boolean, Term).
+
+check_(Pred, Type, Term) :-
+        (   var(Term) -> instantiation_error(must_be/2)
+        ;   call(Pred, Term) -> true
+        ;   type_error(Type, Term, must_be/2)
+        ).
+
+boolean(B) :- ( B == true ; B == false ).
+
+ilist(V) :- var(V), instantiation_error(must_be/2).
+ilist([]).
+ilist([_|Ls]) :- ilist(Ls).
+
+type(type).
+type(integer).
+type(atom).
+type(list).
+type(var).
+type(boolean).
+
+/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+   can_be(Type, Term)
+
+   This predicate is intended for type-checks of built-in predicates.
+
+   It asserts that there is a substitution which, if applied to Term,
+   makes it an instance of Type.
+
+   It corresponds to usage mode ?Term.
+
+   It supports the same types as must_be/2.
+- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
+
+
+can_be(Type, Term) :-
+        must_be(type, Type),
+        (   var(Term) -> true
+        ;   can_(Type, Term) -> true
+        ;   type_error(Type, Term, can_be/2)
+        ).
+
+can_(integer, Term) :- integer(Term).
+can_(atom, Term)    :- atom(Term).
+can_(list, Term)    :- list_or_partial_list(Term).
+can_(boolean, Term) :- boolean(Term).
+
+list_or_partial_list(Var) :- var(Var).
+list_or_partial_list([]).
+list_or_partial_list([_|Ls]) :-
+        list_or_partial_list(Ls).
+
+/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+   Shorthands for throwing ISO errors.
+- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
+
+instantiation_error(Context) :-
+    throw(error(instantiation_error, Context)).
+
+domain_error(Type, Term, Context) :-
+    throw(error(domain_error(Type, Term), Context)).
+
+type_error(Type, Term, Context) :-
+    throw(error(type_error(Type, Term), Context)).