From: Markus Triska <triska@metalevel.at>
Date: Mon, 29 Nov 2021 18:32:55 +0000 (+0100)
Subject: ENHANCED: Correct type error for char_type/2.
X-Git-Tag: v0.9.0~14^2
X-Git-Url: https://git.sagredo.dev/?a=commitdiff_plain;h=79a50de697158a3b2d4087a992c40d23ec8efefb;p=scryer-prolog.git

ENHANCED: Correct type error for char_type/2.

This addresses #905.
---

diff --git a/src/lib/charsio.pl b/src/lib/charsio.pl
index 5ff611f6..85856810 100644
--- a/src/lib/charsio.pl
+++ b/src/lib/charsio.pl
@@ -66,8 +66,7 @@ extend_var_list_([V|Vs], N, VarList, NewVarList, VarType) :-
 
 
 char_type(Char, Type) :-
-    (   var(Char) -> instantiation_error(char_type/2)
-    ;   atom_length(Char, 1) ->
+        must_be(character, Char),
         (   ground(Type) ->
             (   ctype(Type) ->
                 '$char_type'(Char, Type)
@@ -75,9 +74,7 @@ char_type(Char, Type) :-
             )
         ;   ctype(Type),
             '$char_type'(Char, Type)
-        )
-    ;   type_error(in_character, Char, char_type/2)
-    ).
+        ).
 
 
 ctype(alnum).