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Some suggested extensions to existing signatures and mapm #783

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Some suggested extensions to existing signatures and mapm #783

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108 changes: 106 additions & 2 deletions library/apply.pl
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Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,8 @@
maplist/4, % :Pred, ?List, ?List, ?List
maplist/5, % :Pred, ?List, ?List, ?List, ?List
convlist/3, % :Pred, +List, -List
convlist/4, % :Pred, +List, +List, -List
convlist/5, % :Pred, +List, +List, +List, -List
foldl/4, % :Pred, +List, ?V0, ?V
foldl/5, % :Pred, +List1, +List2, ?V0, ?V
foldl/6, % :Pred, +List1, +List2, +List3, ?V0, ?V
Expand All @@ -52,8 +54,11 @@
scanl/4, % :Pred, +List, ?V0, ?Vs
scanl/5, % :Pred, +List1, +List2, ?V0, ?Vs
scanl/6, % :Pred, +List1, +List2, +List3, ?V0, ?Vs
scanl/7 % :Pred, +List1, +List2, +List3, +List4,
scanl/7, % :Pred, +List1, +List2, +List3, +List4,
% ?V0, ?Vs
mapm/4, % :Pred, ?List, ?V0, ?Vn
mapm/5, % :Pred, ?List1, ?List2, ?V0, ?Vn
mapm/6 % :Pred, ?List1, ?List2, ?List3, ?V0, ?Vn
]).
:- autoload(library(error),[must_be/2]).

Expand Down Expand Up @@ -87,14 +92,20 @@
maplist(3, ?, ?, ?),
maplist(4, ?, ?, ?, ?),
convlist(2, +, -),
convlist(3, +, +, -),
convlist(4, +, +, +, -),
foldl(3, +, +, -),
foldl(4, +, +, +, -),
foldl(5, +, +, +, +, -),
foldl(6, +, +, +, +, +, -),
scanl(3, +, +, -),
scanl(4, +, +, +, -),
scanl(5, +, +, +, +, -),
scanl(6, +, +, +, +, +, -).
scanl(6, +, +, +, +, +, -),
mapm(3, ?, ?, ?),
mapm(4, ?, ?, ?, ?),
mapm(5, ?, ?, ?, ?, ?).



%! include(:Goal, +List1, ?List2) is det.
Expand Down Expand Up @@ -251,6 +262,8 @@


%! convlist(:Goal, +ListIn, -ListOut) is det.
%! convlist(:Goal, +ListIn1, +ListIn2, -ListOut) is det.
%! convlist(:Goal, +ListIn1, +ListIn2, +ListIn3, -ListOut) is det.
%
% Similar to maplist/3, but elements for which call(Goal, ElemIn, _)
% fails are omitted from ListOut. For example (using library(yall)):
Expand All @@ -275,6 +288,27 @@
; convlist_(T0, ListOut, Goal)
).

convlist(Goal, ListIn1, ListIn2, ListOut) :-
convlist_(ListIn1, ListIn2, ListOut, Goal).

convlist_([], [], [], _).
convlist_([H0|T0], [H1|T1], ListOut, Goal) :-
( call(Goal, H0, H1, H)
-> ListOut = [H|T],
convlist_(T0, T1, T, Goal)
; convlist_(T0, T1, ListOut, Goal)
).

convlist(Goal, ListIn1, ListIn2, ListIn3, ListOut) :-
convlist_(ListIn1, ListIn2, ListIn3, ListOut, Goal).

convlist_([], [], [], [], _).
convlist_([H0|T0], [H1|T1], [H2|T2], ListOut, Goal) :-
( call(Goal, H0, H1, H2, H)
-> ListOut = [H|T],
convlist_(T0, T1, T2, T, Goal)
; convlist_(T0, T1, T2, ListOut, Goal)
).

/*******************************
* FOLDL *
Expand Down Expand Up @@ -408,6 +442,76 @@
call(Goal, H1, H2, H3, H4, V, VH),
scanl_(T1, T2, T3, T4, Goal, VH, VT).

/*******************************
* MAPM *
*******************************/

%! mapm(:Goal, ?List, ?V0, ?V).
%! mapm(:Goal, ?List1, ?List2, ?V0, ?V).
%! mapm(:Goal, ?List1, ?List2, ?List3, ?V0, ?V).
%
% Map a predicate over a series of lists, threading an final value object
% through the computation "monadically". That is, each call is as though
% it was defined as:
%
% ```
% mapm(G, [X_11, ..., X_1n],
% ...
% [X_m1, ..., X_mn],
% V0, Vn) :-
% call(G, X_11, ... Xm1, V0, V1),
% call(G, X_12, ... Xm2, V1, V2),
% ...
% call(G, X_1n, ... Xmn, V<n-1>, Vn).
% ```
%
% `mapm` behaves like `scanl` retaining only the final value. The actual mode
% is dependent on `Goal` but it is possible to "run it backwards" given `Goal`
% has an admissible mode: `Goal(-X1, ... -Xm, -V<n-1>, +Vn)`.
%
% This is particularly useful in using mapping operations while in DCGs
% where the implicit state must be threaded.
%
% For instance, given the program:
%
% ```
% read_both(X,Y) -->
% [X, Y].
%
% test -->
% mapm(read_both, ["asdf", "fdsa"], ["X", "Y"]).
% ```
%
% ```
% ?- phrase(test, ["asdf", "X", "fdsa", "Y"], L).
% L = [].
% ```

mapm(P,L1,S0,SN) :-
mapm_(L1,S0,SN,P).

mapm_([],S,S,_P).
mapm_([H|T],S0,SN,P) :-
call(P,H,S0,S1),
mapm_(T,S1,SN,P).

mapm(P,L1,L2,S0,SN) :-
mapm_(L1,L2,S0,SN,P).

mapm_([],[],S,S,_P).
mapm_([H|T],[HP|TP],S0,SN,P) :-
call(P,H,HP,S0,S1),
mapm_(T,TP,S1,SN,P).

mapm(P,L1,L2,L3,S0,SN) :-
mapm_(L1,L2,L3,S0,SN,P).

mapm_([],[],[],S,S,_P).
mapm_([H|T],[HP|TP],[HM|TM],S0,SN,P) :-
call(P,H,HP,HM,S0,S1),
mapm_(T,TP,TM,S1,SN,P).



/*******************************
* SANDBOX *
Expand Down