Merge pull request #2 from triska/get_single_char

New feature: RET can now be used as a synonym for "." in the interaction

README.md

@@ -168,8 +168,8 @@ predicates it defines. For example, with the program shown above:
 ;  What = pure_world.
 ```
 
-Press `SPACE` to show further answers, if any exist. Press `.` to
-abort the search and return to the toplevel prompt.
+Press `SPACE` to show further answers, if any exist. Press `RETURN` or
+ `.` to abort the search and return to the toplevel prompt.
 Press `h` to show a help message.
 
 To quit Scryer Prolog, use the standard predicate `halt/0`:

src/prolog/toplevel.pl

@@ -146,24 +146,22 @@
 
 '$read_input'(ThreadedGoals, NewVarList) :-
     get_single_char(C),
-    (  C == w ->
+    (  C = w ->
        nl,
        write('   '),
        '$write_eq'(ThreadedGoals, NewVarList, 0),
        '$read_input'(ThreadedGoals, NewVarList)
-    ;  C == p ->
+    ;  C = p ->
        nl,
        write('   '),
        '$write_eq'(ThreadedGoals, NewVarList, 20),
        '$read_input'(ThreadedGoals, NewVarList)
-    ;  C == (';') ->
+    ;  member(C, [';', ' ', n]) ->
        nl, write(';  '), false
-    ;  C == (' ') ->
-       nl, write(';  '), false
-    ;  C == h ->
+    ;  C = h ->
        '$help_message',
        '$read_input'(ThreadedGoals, NewVarList)
-    ;  C == '.' ->
+    ;  member(C, ['\n', .]) ->
        nl, write(';  ...'), nl
     ; '$read_input'(ThreadedGoals, NewVarList)
     ).
@@ -171,7 +169,7 @@
 '$help_message' :-
     nl, nl,
     write('SPACE, "n" or ";": next solution, if any\n'),
-    write('".": stop enumeration\n'),
+    write('RETURN or ".": stop enumeration\n'),
     write('"h": display this help message\n'),
     write('"w": write terms without depth limit\n'),
     write('"p": print terms with depth limit\n\n').