Say NO to duplicated output

polymani.pl

@@ -59,53 +59,44 @@ polyplay :-
         nl,
         !
     ;
-    (
-        %% Parse the input into a tree
-        parse_input(TIn, LA, NC),
         (
-            %% If the tree is empty, it means nothing was understood
+            %% Parse the input into a tree
-            TIn == void,
+            parse_input(TIn, LA, NC),
-            writeln("I didn't understand what you want."),
+            (
-            writeln(NC)
+                %% If the tree is empty, it means nothing was understood
+                TIn == void,
+                writeln("I didn't understand what you want."),
+                writeln(NC)
+            ;
+                (
+                    %% If there is unconsumed input, it means there was a syntatic error
+                    NC \== [],
+                    write("Syntax error in token: "),
+                    %% Take the head of the list
+                    cons(H, _, NC),
+                    write(H),
+                    nl
+                ;
+                    %% Otherwise, process the parse tree and execute the commands within
+                    process_input(TIn)
+                )
+            )
         ;
-        (
+        %% Parsing failed
-            %% If there is unconsumed input, it means there was a syntatic error
+            writeln("I didn't understand what you want.")
-            NC \== [],
+        ),
-            write("Syntax error in token: "),
-            %% Take the head of the list
-            cons(H, _, NC),
-            write(H),
-            nl
-        ;
-        (
-            %% If the debug_print flag is true, print some extract debug info
-            debug_print(true),
-            write(LA),
-            nl,
-            write(TIn),
-            nl
-        ;
-            %% Otherwise, process the parse tree and execute the commands within
-            process_input(TIn)
-        )
-        )
-        )
-    ;
-    %% Parsing failed
-        writeln("I didn't understand what you want.")
-    ),
     %% Go back to the beginning
     polyplay
     ),
 !.
 
-%% Flag which determines whether to print the parsed input or to process it
+%% process_input(+Tree) is det
-debug_print(false).
-
-%% process_input(+tree) is determines
 %
 %  Execute the commands from the parse tree
 %
+process_input(command(CL, void)) :-
+    %% Process only command left
+    do_process_input(CL).
 process_input(command(CL, TCR)) :-
     %% Process first command
     do_process_input(CL),
@@ -113,11 +104,8 @@ process_input(command(CL, TCR)) :-
     TCR \== void,
     %% recurse
     process_input(TCR).
-process_input(command(CL, void)) :-
-    %% Process only command left
-    do_process_input(CL).
 
-%% do_process_input(+tree) is det
+%% do_process_input(+Tree) is det
 %
 %  Process a single command from the input
 %  Takes, as the only argument, the tree representing
@@ -261,9 +249,9 @@ do_process_input(store_multiplication(TN, PT, V)) :-
     polynomial_tree_to_polynomial(PT, P),
     (
         not(number(N)),
-	scalepoly(N, P, P2)
+        scalepoly(N, P, P2)
     ;
-	number(N),
+        number(N),
         scalepoly(P, N, P2)
     ),
     simpoly(P2, SP),
@@ -280,9 +268,9 @@ do_process_input(multiply(TN, PT)) :-
     %% Use function from UI layer
     (
         not(number(N)),
-	scalepoly(N, P, P2)
+        scalepoly(N, P, P2)
     ;
-	number(N),
+        number(N),
         scalepoly(P, N, P2)
     ),
     simpoly(P2, SP),