function
boot.janet on line 1581, column 1
(group-by f ind)
Group elements of `ind` by a function `f` and put the results into
a new table. The keys of the table are the distinct return values
from calling `f` on the elements of `ind`. The values of the table
are arrays of all elements of `ind` for which `f` called on the
element equals that corresponding key.
(group-by odd? [1 2 3 5 6])
# =>
@{false @[2 6] true @[1 3 5]}(group-by
(fn [i] (i :label))
[{:label 'A :value 4} {:label 'A :value 3} {:label 'B :value 5}])
# @{A @[{:label A :value 4} {:label A :value 3}] B @[{:label B :value 5}]}