'a' should be callable

[mb64]

Scryer Prolog assures me that 'a' and a are the same thing, but 'a'. and a. give different errors in the REPL:

$ scryer-prolog 
?- 'a' = a.
   true.
?- a.
caught: error(existence_error(procedure,a/0),a/0)
?- 'a'.
caught: error(type_error(callable,a),call/2)

I would expect them to behave identically.

[UWN]

Strictly speaking, the top level may do what it wants with errors since the toplevel is out of scope. However, taking the essence of your case makes it truly non-conforming:

?- catch('a',error(E,_),true).
   E = type_error(callable,a).   % unexpected

Expected: E = existence_error(procedure,a/0).

[triska]

This works exactly as expected now:

?- a.
caught: error(existence_error(procedure,a/0),a/0)