dif/2 with different open variables

[UWN]

:- use_module(library(lambda)).

til([G_0, (A,B,D)]) :-
   G_0 = (D,A,B),
   D = dif(_,_),
   skel(B),
   f(G_0).

f((dif(A,B),A=B/[],B=C/A/C)).

skel(_=_/_/_).

?- {N,Vs} +\ ( til(L),nth1(N,L,G), call_residue_vars(G,Vs) ).
   N = 1, Vs = [_A], unexpected
;  N = 2, Vs = []
;  false.

[UWN]

?- {N,Constrs} +\ ( til(L),nth1(N,L,G), call_residue_vars(G,Vs), copy_term(Vs,_,Constrs) ).
   N = 1, Constrs = [dif:dif(_A/(_A/(_A/_/_A/[])/_A/[])/_A/[],_A/(_A/(_A/_/_A/[])/_A/[])/_A)], unexpected
;  N = 2, Constrs = []
;  false.

So copy_term/3 sees this unexpected dangeling constraint, but the top level loops denies its existence...

[infradig]

I guess related to #443

…

On Sun, Jan 28, 2024 at 6:27 AM UWN ***@***.***> wrote: ?- {N,Constrs} +\ ( til(L),nth1(N,L,G), call_residue_vars(G,Vs), copy_term(Vs,_,Constrs) ). N = 1, Constrs = [dif:dif(_A/(_A/(_A/_/_A/[])/_A/[])/_A/[],_A/(_A/(_A/_/_A/[])/_A/[])/_A)], unexpected ; N = 2, Constrs = [] ; false. So copy_term/3 sees this unexpected dangeling constraint, but the top level loops denies its existence... — Reply to this email directly, view it on GitHub <#481 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AFNKSEWLESBBLYWVH5K6WETYQVPLTAVCNFSM6AAAAABCNTCPEGVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTSMJTGMZDMOBVGM> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[UWN]

Now:

?- {N,Constrs} +\ ( til(L),nth1(N,L,G), call_residue_vars(G,Vs), copy_term(Vs,_,Constrs) ).
   N = 1, Constrs = [[]], unexpected
;  N = 2, Constrs = []

[UWN]

Now, v2.62.4:

?- {N,Constrs} +\ ( til(L),nth1(N,L,G), call_residue_vars(G,Vs), copy_term(Vs,_,Constrs) ).
   N = 1, Constrs = [dif:dif(_A/(_A/(_A/(_A/(_A/(_A/_B/_A/[])/_A/[])/_A/[])/_A/[])/_A/[])/_A/[],_A/(_A/(_A/(_A/(_A/(_A/_B/_A/[])/_A/[])/_A/[])/_A/[])/_A/[])/_A)], unexpected
;  N = 2, Constrs = []
;  false.
``