Я ☞ Snippets ☞ Filtering elements within data structures

Filtering using binding operator

Let’s say we want some List to contain only even values. We won’t reveal even implementation, it’s enough to know its type:

even: Integer `AR__` Integer `S` Integer

So that this even expression raturns Either value, That value is even, This value is odd.

We can use yok operator to filter out elements based on predicate output, using la operator we case split on even output - on This - Erase, on That - Store:

[1,2,3,4,5,6] `yok_` Check `ha__` Erase `la` Store `ha__` even

This is how yok operation would look like if we instantiate it:

Full source code