function
boot.janet on line 952, column 1
(keep pred ind)
Given a predicate `pred`, return a new array containing the truthy
results of applying `pred` to each element in the indexed
collection `ind`. This is different from `filter` which returns an
array of the original elements where the predicate is truthy.
(def person-ids {"Alice" 42 "Bob" 23})
(keep person-ids ["Carl" "Bob" "Alice"]) # -> @[23 42]
(filter person-ids ["Carl" "Bob" "Alice"]) # -> @["Bob" "Alice"]
(map person-ids ["Carl" "Bob" "Alice"]) # -> @[nil 23 42]