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Minor edits.

This commit is contained in:
Simon Forman 2020-01-31 12:01:13 -08:00
parent a14a55defb
commit cfab1cf3c8
1 changed files with 19 additions and 19 deletions
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thun/thun.pl
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@ -73,9 +73,6 @@ joy(InputString, StackIn, StackOut) :-
╚██████╔╝██║ ██║██║ ██║██║ ╚═╝ ██║██║ ╚═╝ ██║██║ ██║██║ ██║ ╚██████╔╝██║ ██║██║ ██║██║ ╚═╝ ██║██║ ╚═╝ ██║██║ ██║██║ ██║
╚═════╝ ╚═╝ ╚═╝╚═╝ ╚═╝╚═╝ ╚═╝╚═╝ ╚═╝╚═╝ ╚═╝╚═╝ ╚═╝ ╚═════╝ ╚═╝ ╚═╝╚═╝ ╚═╝╚═╝ ╚═╝╚═╝ ╚═╝╚═╝ ╚═╝╚═╝ ╚═╝
The grammar of Joy is very simple. A Joy expression is zero or more Joy The grammar of Joy is very simple. A Joy expression is zero or more Joy
terms separated by blanks, and terms can be either integers, Booleans, terms separated by blanks, and terms can be either integers, Booleans,
quoted Joy expressions, or symbols (names of functions.) quoted Joy expressions, or symbols (names of functions.)
@ -170,27 +167,30 @@ thun(bool(C), [A|B], D, E) :- thun(A, B, [bool(C)|D], E).
thun(list(A), [], B, [list(A)|B]). thun(list(A), [], B, [list(A)|B]).
thun(list(C), [A|B], D, E) :- thun(A, B, [list(C)|D], E). thun(list(C), [A|B], D, E) :- thun(A, B, [list(C)|D], E).
% Partial reduction for func/3 cases works. % Partial reduction works for func/3 cases.
thun(symbol(A), [], B, C) :- func(A, B, C). thun(symbol(A), [], B, C) :- func(A, B, C).
thun(symbol(A), [C|D], B, F) :- func(A, B, E), thun(C, D, E, F). thun(symbol(A), [C|D], B, F) :- func(A, B, E), thun(C, D, E, F).
% Combinators look ok too. % Combinators look ok too.
thun(symbol(A), D, B, C) :- combo(A, B, C, D, []). % thun(symbol(A), D, B, C) :- combo(A, B, C, D, []).
thun(symbol(A), C, B, G) :- combo(A, B, F, C, [D|E]), thun(D, E, F, G). % thun(symbol(A), C, B, G) :- combo(A, B, F, C, [D|E]), thun(D, E, F, G).
% I think the order of these two rules should be reversed because % However, in this case, I think the original version will be more
% it will be pretty rare for a combinator to result in a null % efficient.
% expression and we don't want to process combo/5 twice just to
% notice that, eh? Swap the rules and add green cuts after combo/5
% and that should make it more efficient.
% Ach! THe "green" cuts would mess up multi-rule combinators! D'oh! thun(symbol(Combo), E, Si, So) :- combo(Combo, Si, S, E, Eo), thun(Eo, S, So).
% Neither functions nor definitions can affect the expression so we % In the reduced rules Prolog will redo all the work of the combo/5
% don't need to do similar gardening to those rules. The unification % predicate on backtracking through the second rule. It will try combo/5,
% of the head clauses will distinguish the cases for them. % which usually won't end in Eo=[] so the first rule fails, then it will
% try combo/5 again in the second rule. In this form, after combo/5 has
% completed Prolog has computed Eo and can index on it for thun/3.
%
% Neither functions nor definitions can affect the expression so this
% doesn't apply to those rules. The unification of the head clauses will
% distinguish the cases for them.
% Definitions don't work though (See "Partial Reducer" section below.) % Definitions don't work though (See "Partial Reducer" section below.)
% I hand-wrote the def/3 cases here. (Maybe if append/3 was reduced?) % I hand-wrote the def/3 cases here. (Maybe if append/3 was reduced?)
@ -1104,9 +1104,9 @@ thunder([ % Source code for thun/4.
(thun( int(I), E, Si, So) :- thun(E, [ int(I)|Si], So)), (thun( int(I), E, Si, So) :- thun(E, [ int(I)|Si], So)),
(thun(bool(B), E, Si, So) :- thun(E, [bool(B)|Si], So)), (thun(bool(B), E, Si, So) :- thun(E, [bool(B)|Si], So)),
(thun(list(L), E, Si, So) :- thun(E, [list(L)|Si], So)), (thun(list(L), E, Si, So) :- thun(E, [list(L)|Si], So)),
(thun(symbol(Def), E, Si, So) :- def(Def, Body), append(Body, E, [T|Eo]), thun(T, Eo, Si, So)), % (thun(symbol(Def), E, Si, So) :- def(Def, Body), append(Body, E, [T|Eo]), thun(T, Eo, Si, So)),
(thun(symbol(Func), E, Si, So) :- func(Func, Si, S), thun(E, S, So)), (thun(symbol(Func), E, Si, So) :- func(Func, Si, S), thun(E, S, So))
(thun(symbol(Combo), E, Si, So) :- combo(Combo, Si, S, E, Eo), thun(Eo, S, So)) % (thun(symbol(Combo), E, Si, So) :- combo(Combo, Si, S, E, Eo), thun(Eo, S, So))
]). ]).
/* /*