I’m using: SWI-Prolog version 8.1.9 I saw this text on the docs page for freeze/2: https://www.swi-prolog.org/pldoc/doc_for?object=freeze/2 Delay the execution of Goal until Var is bound (i.e. is not a variable or attributed variable). If Varis bound on entry freeze/2 is equivalent to call/1 . Th…

While I understand the concept of coroutine , I do not have any experience with using freeze/2 in SWI-Prolog. In such cases I search the source code for SWI-Prolog at GitHub and in this case there appears to many examples and test cases.

freeze/2 delays a predicate call until the variable is instantiated. (The more general form is when/2) Attributed variables allow you to do something interesting with unification. https://www.swi-prolog.org/pldoc/man?section=attvar

Can I use freeze/2 to detect a variable being instantiated, for debugging purposes?

Help!

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Can I use freeze/2 to detect a variable being instantiated, for debugging purposes?

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