diff --git a/.gitignore b/.gitignore
index 265c8cd..280632a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,3 +15,4 @@ implementations/Nim/joy
 implementations/Python/joy
 docs/notebooks/.ipynb_checkpoints
 joy.py.*
+joy_to_ast
diff --git a/implementations/GNUProlog/joy_to_ast.prolog b/implementations/GNUProlog/joy_to_ast.prolog
new file mode 100644
index 0000000..7219cc4
--- /dev/null
+++ b/implementations/GNUProlog/joy_to_ast.prolog
@@ -0,0 +1,86 @@
+
+
+stdin_to_codes(Codes) :-
+    % Pass in and discard atom 'code' to prime stdin_to_codes/2.
+    stdin_to_codes(code, [code|Codes]).
+
+stdin_to_codes(-1, []) :- !.
+stdin_to_codes(Code, [Code|Codes]) :-
+    get_code(NextCode),
+    stdin_to_codes(NextCode, Codes).
+
+%
+%joy(InputString, StackIn, StackOut) :-
+%    text_to_expression(InputString, Expression),
+%    !,
+%    thun(Expression, StackIn, StackOut).
+%
+
+joy_lex([tok(Token)|Ls]) --> chars(Token), !, joy_lex(Ls).
+joy_lex([  lbracket|Ls]) --> "[",          !, joy_lex(Ls).
+joy_lex([  rbracket|Ls]) --> "]",          !, joy_lex(Ls).
+
+joy_lex(Ls) --> blank, !, joy_lex(Ls).
+
+joy_lex([]) --> [].
+
+
+% Then parse the tokens converting them to Prolog values and building up
+% the list structures (if any.)
+
+joy_parse([J|Js]) --> joy_term(J), !, joy_parse(Js).
+joy_parse([]) --> [].
+
+joy_term(list(J)) --> [lbracket], !, joy_parse(J), [rbracket].
+joy_term(Token) --> [tok(Codes)], {joy_token(Token, Codes)}.
+
+joy_token(int(I), Codes) :- catch(number_codes(I, Codes), _Err, fail), !.
+joy_token(bool(true), "true") :- !.
+joy_token(bool(false), "false") :- !.
+joy_token(symbol(S), Codes) :- atom_codes(S, Codes).
+
+text_to_expression(Text, Expression) :-
+    phrase(joy_lex(Tokens), Text), !,
+    phrase(joy_parse(Expression), Tokens).
+
+% Apologies for all the (green, I hope) cuts.  The strength of the Joy
+% syntax is that it's uninteresting.
+
+chars([Ch|Rest]) --> char(Ch), chars(Rest).
+chars([Ch])      --> char(Ch).
+
+char(Ch) --> \+ blank, [Ch], { Ch \== 0'[, Ch \== 0'] }.
+
+
+blank --> [9].
+blank --> [10].
+blank --> [11].
+blank --> [12].
+blank --> [13].
+blank --> [32].
+blank --> [194, 133].
+blank --> [194, 160].
+blank --> [225, 154, 128].
+blank --> [226, 128, 128].
+blank --> [226, 128, 129].
+blank --> [226, 128, 130].
+blank --> [226, 128, 131].
+blank --> [226, 128, 132].
+blank --> [226, 128, 133].
+blank --> [226, 128, 134].
+blank --> [226, 128, 135].
+blank --> [226, 128, 136].
+blank --> [226, 128, 137].
+blank --> [226, 128, 138].
+blank --> [226, 128, 168].
+blank --> [226, 128, 169].
+blank --> [226, 128, 175].
+blank --> [226, 129, 159].
+blank --> [227, 128, 128].
+
+
+:- initialization((
+    stdin_to_codes(Codes),
+    text_to_expression(Codes, Expr),
+    print(Expr), print('\n')
+    )).
\ No newline at end of file