CODEWITHSUNDEEP
prolog
MrJalapeno
MrJalapeno

Reputation: 1662

I/O in prolog: Error: Arguments are not sufficiently instantiated, no further information

So I'm working with I/O in prolog and I'm getting

Error: Arguments are not sufficiently instantiated

What puzzles me is why I'm not getting any information on what predicate is causing the issue.

(EDIT: In the image L2 is the name of the prolog-file shown to the left, [L2.pl] gives the same error.)

enter image description here

What the program should do:
The program is supposed to verify a temporal logic statement. It will read a file (Input) and from the file get: an adjacency list of how states are connected (T); another adjacency list of what formulas each state contains (L); a state (S) and a temporal logic formula (F). Then it should check if the formula F is true in state S.

Here's example of how the Input-file can look:

[[s0, [s0, s2, s1]],
 [s1, [s1, s0]],
 [s2, [s0, s2]]].

[[s0, [p, q]],
 [s1, [p]],
 [s2, [q, r]]].

s0.

p

Right now I've only implemented a trivial check to see if formula F is in state S. But the program don't want to compile and I don't understand why.

Upvotes: 0

Views: 106

Answers (1)

lurker
lurker

Reputation: 58244

In Prolog, if you enter an identifier that is capitalized, it's considered a variable, even if it's used in the query to load a file:

?- [L2].

This attempts to load (or consult) a file whose name is given by the variable, L2. Of course, L2 is not instantiated in the above, so this will fail with an instantiation error. For the same reason, the following will also fail:

?- [L2.pl].

The consult [...] requires an atom for a file name. If you want an atom that starts with a capital letter, you need to use quotes. So the following will work:

?- ['L2'].

Or

?- ['L2.pl'].

Upvotes: 3

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