Execute HQ9+: Difference between revisions

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 <lang Erlang>% hq9+ Erlang implementation (JWL)
 % http://www.erlang.org/
 -module(hq9p).
 -export([main/1]).
+hello() ->
-%% Helper function printing bottles
+  io:format("Hello world!~n", []).
-bottle(N) ->
-    case N of
--> io:format("One bottle ");
-	_ -> io:format("~w bottles ", [N])
-    end.
+prog(Prog) ->
-%% Implementation of machine instructions
+  io:format("~s~n", [Prog]).
-hello() ->
+bottle(0) ->
-    io:format("Hello world!~n").
+  io:format("No more bottles of beer ");
+bottle(1) ->
+  io:format("1 bottle of beer ");
+bottle(N) when N > 0 ->
-prog(Prog) ->
-    io:format("~s~n", [Prog]).
+  io:format("~w bottles of beer ", [N]).
 beer(0) ->
+  bottle(0), io:format("on the wall~n"),
-    io:format("No more bottles of beer on the wall~nNo more bottles of beer on the wall~nGo to the store and buy some more~n99 bottles of beer on the wall.~n");
+  bottle(0), io:format("on the wall~nGo to the store and buy some more~n"),
+  io:format("99 bottles of beer on the wall.~n");
 beer(N) ->
-    io:format("~n"),
+  bottle(N), io:format("on the wall~n"),
-    bottle(N), io:format("of beer on the wall~n"),
+  bottle(N), io:format("~nTake one down and pass it around~n"),
-    bottle(N), io:format("of beer~nTake one down and pass it around~n"),
+  bottle(N-1), io:format("on the wall~n~n"),
+  beer(N-1).
-    bottle(N-1), io:format("of beer on the wall~n"),
-    beer(N-1).
 inc(Acc) ->
-    Acc+1.
+  Acc+1.
-%% Execute a single instruction
 execute(Instruction, Prog, Acc) ->
-    case Instruction of
+  case Instruction of
-        $H -> hello(), Acc;
+    $H -> hello(), Acc;
-        $Q -> prog(Prog), Acc;
+    $Q -> prog(Prog), Acc;
-        $9 -> beer(99), Acc;
+    $9 -> beer(99), Acc;
-        $+ -> inc(Acc);
+    $+ -> inc(Acc);
-         _ -> io:format("Invalid instruction: ~c~n", [Instruction]),
+       _ -> io:format("Invalid instruction: ~c~n", [Instruction]), Acc
+  end.
-                 Acc
-    end.
-%% Empty program, Program string, Accu
 main([], _Prog, Acc) ->
-    Acc;
+  Acc;
-%% Instruction, Rest of program, Program string, Accu
 main([Instruction | Rest], Prog, Acc) ->
-    NewAcc = execute(Instruction, Prog, Acc),
+  NewAcc = execute(Instruction, Prog, Acc),
-    main(Rest, Prog, NewAcc).
+  main(Rest, Prog, NewAcc).
-%% Compile and execute
 main(Prog) ->
-    Compiled = string:to_upper(Prog),
+  Compiled = string:to_upper(Prog),
-    main(Compiled, Prog, 0).
+  main(Compiled, Prog, 0).
-}</lang>
+</lang>
 =={{header|Forth}}==