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I'm not able to run this code, what exactly do I have to say about the list to allow maplist/2 to run all_distinct/1?

Solution = [A, B, C, D, E, F, G, H, I], 
Solution ins 1..9, 
maplist(all_distinct, Solution).

I get ERROR: Arguments are not sufficiently instantiated. I understand that I'm not telling it enough about the list of numbers, but I don't know what I need to tell it. I want a list of 9 different numbers 1 through 9.

Here's a trace when I try to execute:

   Call: (7) puzzle(_G548) ? creep
   Call: (8) _G548=[_G656, _G659, _G662, _G665, _G668, _G671, _G674, _G677|...] ? creep
   Exit: (8) [_G656, _G659, _G662, _G665, _G668, _G671, _G674, _G677|...]=[_G656, _G659, _G662, _G665, _G668, _G671, _G674, _G677|...] ? creep
   Call: (8) clpfd: ([_G656, _G659, _G662, _G665, _G668, _G671, _G674|...]ins 1..9) ? creep
   Call: (9) error:must_be(list, [_G656, _G659, _G662, _G665, _G668, _G671, _G674|...]) ? creep
   Exit: (9) error:must_be(list, [_G656, _G659, _G662, _G665, _G668, _G671, _G674|...]) ? creep
   Call: (9) clpfd:'__aux_maplist/2_fd_variable+0'([_G656, _G659, _G662, _G665, _G668, _G671, _G674|...]) ? creep
   Call: (10) clpfd:fd_variable(_G656) ? creep
   Call: (11) var(_G656) ? creep
   Exit: (11) var(_G656) ? creep
   Call: (11) true ? creep
   Exit: (11) true ? creep
   Exit: (10) clpfd:fd_variable(_G656) ? creep
   Call: (10) clpfd:'__aux_maplist/2_fd_variable+0'([_G659, _G662, _G665, _G668, _G671, _G674, _G677|...]) ? creep

It looks like ins/2 might be not working and then still passing off to maplist/2? I've got no idea what is happening.

false
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jboulter11
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    Actually, a `type_error(list,X)` would have been more helpful – false Feb 10 '15 at 14:32
  • @false You should probably report this as a bug –  Feb 10 '15 at 14:36
  • @Boris: Filed 2013-08-08 as i3a#314. But it is a very hairy situation, since a variable is commonly not associated with a type error. Yes, there is no instance that would be a valid term, so a type error seems to make a lot of sense, but it still is on the edge. – false Feb 10 '15 at 14:54

1 Answers1

4

What you are doing is that you are making a list of variables, Solutions, and then Solutions ins 1..9 makes each variable an integer between 1 and 9.

all_distinct/1 expects a list, not an integer.

So, if you want a list of 9 distinct integers:

?- Solutions = [A,B,C,D,E,F,G,H,I],
   Solutions ins 1..9,
   all_distinct(Solutions).
L = [A, B, C, D, E, F, G, H, I],
A in 1..9,
all_distinct([A, B, C, D, E, F, G, H|...]),
B in 1..9,
C in 1..9,
D in 1..9,
E in 1..9,
F in 1..9,
G in 1..9,
H in 1..9,
I in 1..9.