From 0bfb6988d8768b7d01453cc8886e0f57e9037e53 Mon Sep 17 00:00:00 2001
From: logicmoo <logicmoo@gmail.com>
Date: Thu, 29 Aug 2024 04:03:57 -0700
Subject: [PATCH] variant_by_type

---
 src/canary/metta_eval.pl | 28 ++++++++++++++++++++--------
 1 file changed, 20 insertions(+), 8 deletions(-)

diff --git a/src/canary/metta_eval.pl b/src/canary/metta_eval.pl
index e73be13f868..da5789a84d4 100755
--- a/src/canary/metta_eval.pl
+++ b/src/canary/metta_eval.pl
@@ -1689,9 +1689,10 @@
     fromNumber(N,RetVal), check_returnval(Eq,RetType,RetVal).
 */
 
-%% lazy_union(+E1_Call1, +E2_Call2, -E) is nondet.
+%% lazy_union(:P2, +E1_Call1, +E2_Call2, -E) is nondet.
 %  - Performs a union operation using lazy evaluation
 % Arguments:
+%  - P2: Any arity 2 predicate
 %  - E1^Call1: The first goal (Call1) generating elements (E1)
 %  - E2^Call2: The second goal (Call2) generating elements (E2)
 %  - E: The resulting element that is part of the union of the two sets
@@ -1709,19 +1710,21 @@
     ).
 
 
+variant_by_type(X,Y):- var(X),!,X==Y.
+variant_by_type(X,Y):- X=@=Y.
+
 eval_20(Eq,RetType,Depth,Self,['unique',Eval],RetVal):- !,
    term_variables(Eval+RetVal,Vars),
    no_repeats_var(YY),
    eval_20(Eq,RetType,Depth,Self,Eval,RetVal),YY=Vars.
 
 eval_20(Eq,RetType,Depth,Self,['pred-unique',P2,Eval],RetVal):- !,
-   term_variables(Eval+RetVal,Vars),
    no_repeats_var(P2,YY),
-   eval_20(Eq,RetType,Depth,Self,Eval,RetVal),YY=Vars.
+   eval_20(Eq,RetType,Depth,Self,Eval,RetVal),YY=RetVal.
 
 
 eval_20(Eq,RetType,Depth,Self,['subtraction',Eval1,Eval2],RetVal):- !,
-    lazy_subtraction(=@=,RetVal1^eval_args(Eq,RetType,Depth,Self,Eval1,RetVal1),
+    lazy_subtraction(variant_by_type,RetVal1^eval_args(Eq,RetType,Depth,Self,Eval1,RetVal1),
                   RetVal2^eval_args(Eq,RetType,Depth,Self,Eval2,RetVal2),
                   RetVal).
 
@@ -1731,7 +1734,7 @@
                   RetVal).
 
 eval_20(Eq,RetType,Depth,Self,['union',Eval1,Eval2],RetVal):- !,
-    lazy_union(=@=,RetVal1^eval_args(Eq,RetType,Depth,Self,Eval1,RetVal1),
+    lazy_union(variant_by_type,RetVal1^eval_args(Eq,RetType,Depth,Self,Eval1,RetVal1),
                   RetVal2^eval_args(Eq,RetType,Depth,Self,Eval2,RetVal2),
                   RetVal).
 
@@ -1744,7 +1747,7 @@
 % !, Atom=[_|CDR],!,do_expander(Eq,RetType,Atom_list, CDR_Y ).
 
 eval_20(Eq,RetType,Depth,Self,['intersection',Eval1,Eval2],RetVal):- !,
-    lazy_intersection(=@=,RetVal1^eval_args(Eq,RetType,Depth,Self,Eval1,RetVal1),
+    lazy_intersection(variant_by_type,RetVal1^eval_args(Eq,RetType,Depth,Self,Eval1,RetVal1),
                   RetVal2^eval_args(Eq,RetType,Depth,Self,Eval2,RetVal2),
                   RetVal).
 
@@ -1753,20 +1756,29 @@
                   RetVal2^eval_args(Eq,RetType,Depth,Self,Eval2,RetVal2),
                   RetVal).
 
+%% lazy_intersection(:P2, +E1_Call1, +E2_Call2, -E) is nondet.
+%  - Performs a intersection operation using lazy evaluation.
+%  - It intersects elements generated by Call2 from those generated by Call1.
+% Arguments:
+%  - P2: Any arity 2 predicate
+%  - E1^Call1: The first goal (Call1) generating elements (E1).
+%  - E2^Call2: The second goal (Call2) generating elements (E2).
+%  - E: The resulting element after subtracting elements of the second set from the first set.
 lazy_intersection(P2, E1^Call1, E2^Call2, E1) :-
     % Step 1: Evaluate Call1 to generate E1
     call(Call1),
     % Step 2: Use lazy_findall/3 to declare that all elements satisfying Call2 are supposedly in List2
     lazy_findall(E2, Call2, List2),
-    % Step 3: Perform the subtraction logic
+    % Step 3: Perform the intersection logic
     % Only return E1 if it is not a member of List2
     member(E2, List2), call(P2,E1,E2).
 
 
-%% lazy_subtraction(+E1_Call1, +E2_Call2, -E) is nondet.
+%% lazy_subtraction(:P2, +E1_Call1, +E2_Call2, -E) is nondet.
 %  - Performs a subtraction operation using lazy evaluation.
 %  - It subtracts elements generated by Call2 from those generated by Call1.
 % Arguments:
+%  - P2: Any arity 2 predicate
 %  - E1^Call1: The first goal (Call1) generating elements (E1).
 %  - E2^Call2: The second goal (Call2) generating elements (E2).
 %  - E: The resulting element after subtracting elements of the second set from the first set.