add library(reif)

src/prolog/lib/reif.pl

@@ -0,0 +1,73 @@
+:- module(reif, [if_/3, (=)/3, (,)/3, (;)/3, cond_t/3, dif/3,
+		 memberd_t/3, tfilter/3, tmember/2, tmember_t/3,
+		 tpartition/4]).
+
+:- use_module(library(control), [(\=)/2]).
+:- use_module(library(dif)).
+
+/* in essence, '$reify_switch'(T, Then_0, Else_0) is this:
+    (  T == true -> call(Then_0)
+    ;  T == false -> call(Else_0)
+    ;  nonvar(T) -> throw(error(type_error(boolean, T), _))
+    ;  throw(error(instantiation_error, _))
+    ).
+    but without creating choice points.
+*/
+
+if_(If_1, Then_0, Else_0) :-
+    call(If_1, T),
+    '$reify_switch'(T, Then_0, Else_0).
+
+=(X, Y, T) :-
+    (  X == Y -> T = true
+    ;  X \= Y -> T = false
+    ;  T = true, X = Y
+    ;  T = false, dif(X, Y)
+    ).
+
+dif(X, Y, T) :-
+  =(X, Y, NT),
+  non(NT, T).
+
+non(true, false).
+non(false, true).
+
+tfilter(C_2, Es, Fs) :-
+   i_tfilter(Es, C_2, Fs).
+
+i_tfilter([], _, []).
+i_tfilter([E|Es], C_2, Fs0) :-
+   if_(call(C_2, E), Fs0 = [E|Fs], Fs0 = Fs),
+   i_tfilter(Es, C_2, Fs).
+
+tpartition(P_2, Xs, Ts, Fs) :-
+   i_tpartition(Xs, P_2, Ts, Fs).
+
+i_tpartition([], _P_2, [], []).
+i_tpartition([X|Xs], P_2, Ts0, Fs0) :-
+   if_( call(P_2, X)
+      , ( Ts0 = [X|Ts], Fs0 = Fs )
+      , ( Fs0 = [X|Fs], Ts0 = Ts ) ),
+   i_tpartition(Xs, P_2, Ts, Fs).
+
+','(A_1, B_1, T) :-
+    if_(A_1, call(B_1, T), T = false).
+
+';'(A_1, B_1, T) :-
+    if_(A_1, T = true, call(B_1, T)).
+
+cond_t(If_1, Then_0, T) :-
+   if_(If_1, ( Then_0, T = true ), T = false ).
+
+memberd_t(E, Xs, T) :-
+   i_memberd_t(Xs, E, T).
+
+i_memberd_t([], _, false).
+i_memberd_t([X|Xs], E, T) :-
+   if_( X = E, T = true, i_memberd_t(Xs, E, T) ).
+
+tmember(P_2, [X|Xs]) :-
+   if_( call(P_2, X), true, tmember(P_2, Xs) ).
+
+tmember_t(P_2, [X|Xs], T) :-
+   if_( call(P_2, X), T = true, tmember_t(P_2, Xs, T) ).