is it possible to implement the specification patt...

# announcements

[Matthew Good]

is it possible to implement the specification pattern in kotlin?

as i tried https://dzone.com/articles/java-using-specification but i get the following undefined references:
Predicate
CriteriaBuilder
Root

[Dominaezzz]

If C# can do it, Kotlin can do it.

[Pavlo Liapota]

They are JPA classes
https://www.objectdb.com/api/java/jpa/criteria/CriteriaBuilder

[Matthew Good]

oh

[Matthew Good]

the specification pattern is used to implement logic such as val b = v("1").and("2").and("3").and("4") in

val i = txt("1234")

val a = v("1234")

val b = v("1").and("2").and("3").and("4")

AssertEquals(a.peek() == b.peek())
// fails if both are not equal

in applications such as parser combinators right?

[Casey Brooks]

I’ve actually built a small library for this https://copper-leaf.github.io/trellis/

[Casey Brooks]

Pretty easy to do overall, relies heavily on generics and extension functions

[Matthew Good]

ill check it out

[Matthew Good]

also @Casey Brooks https://kotlinlang.slack.com/archives/C0922A726/p1556543764297600