List processing at fault

[flexoron]

?- L = ['A','B'('C')],length(L,N).
   L = ['A','B'('C')], N = 2.

?- L = ['A','B' ('C')],length(L,N).
   false.
?- L = ['A','B' ('C')].
   L = ['A','B'|'C']. % unexpected

[infradig]

Interesting...

?- X = [1,f (2),3].
Error: syntax error, operator expected before parens, user:1
?- X = [1,'f' (2),3].
   X = [1,f|2].
?- 

[flexoron]

?- L = ['f' (.)]. % fixed
Error: syntax error, operator expected before parens, user:1

?- L = ['.' (f)]. % foxed
   L = ['.'|f].
?- 

[flexoron]

v2.56.29
Looks like some operators are involved, too

?- L = [',' (x)].
   L = [','|x].
?- L = ['*->' (x)].
   L = [*->|x].
?- L = ['->' (x)].
   L = [->|x].
?- L = [';' (x)].
   L = [;|x].
?- L = ['^' (x)].
   L = [^|x].

[flexoron]

v2.56.30
Now this, again, seems a problem:

?- L = ['.' ('.')].
Error: syntax error, operator expected before parens, user:1
?- L = ['.'('.')].
   L = ['.'('.')].

?- op(1,fy,'.').
   true.
?- L = ['.'('.')].
   L = ['.' ('.')]. % printed but not accepted:
?- L = ['.' ('.')].
Error: syntax error, operator expected before parens, user:1
?-