# Is the definition of "predicate" correct in the Glossary of Terms?

**URL:** <https://swi-prolog.discourse.group/t/is-the-definition-of-predicate-correct-in-the-glossary-of-terms/2807>\
**Category:** General\
**Created:** [August 20, 2020, 12:14pm UTC](https://swi-prolog.discourse.group/t/is-the-definition-of-predicate-correct-in-the-glossary-of-terms/2807 "2020-08-20T12:14:40Z")\
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**Author:** ![Boris](https://yyz2.discourse-cdn.com/free1/user_avatar/swi-prolog.discourse.group/boris/32/7486_2.png) [@Boris](https://swi-prolog.discourse.group/u/Boris)\
**Post date:** [August 21, 2020, 7:04am UTC](https://swi-prolog.discourse.group/t/is-the-definition-of-predicate-correct-in-the-glossary-of-terms/2807/13 "2020-08-21T07:04:45Z")

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> [@joeblog](#):
>
> The definition that a “predicate is a function that returns a boolean” is nice and simple and clear, so I like it.

😃 H about “a callable that returns a value testable as `bool`”?

But then again, those are “functional programming” predicates. Apparently you find them everywhere these days, I didn’t realize that…

Java: [`Interface Predicate<T>`](https://docs.oracle.com/javase/8/docs/api/java/util/function/Predicate.html)

Javascript: [“… _callback_: function is a predicate, to test each element of the array…”](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter)

Haskell: all over the place, really…

You can also find it all over the place when people talk about Python…

I suspect “predicate” is also used when people talk about SQL…

I guess the list goes on.

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