I’m not sure I understand the term ‘predicate’.. is it basically any expression that returns a boolean value ?

I think that is accurate

that’s correct ivar. https://en.wikipedia.org/wiki/Predicate_(mathematical_logic)

thanks, I saw predicate used in a clojure context and actually consulted the above wikipedia page, but was not totally sure

ivar a predicate practically can be thought of as what you said

if you are filtering over a vector you pass a “predicate” function to the filter function and any elements of the vector which pass the predicate are kept in the new vector

(filterv even? [1 2 3 4 5]) -> [2, 4]