Currying.fold

--
-- Currying
-- http://rosettacode.org/wiki/Currying#Fold
--
-- http://en.wikipedia.org/wiki/Currying
-- https://github.com/JuliaLang/julia/issues/554
-- http://opendylan.org/documentation/library-reference/dylan/alternative-curry-syntax.html

Fold supports natural parameter currying.

--
-- (((curry +) 3) 2) ; =>5


sum x y = x + y

alter_elements = !(map ~ [1, 2, 3])

alter_elements (+ 1)
--> [2, 3, 4]

--> elements_length = \ x -> map length ~1

~1 + ~1

elements_length [[1, 2, 3], [1, 2], [1]]


def visits_duration_by_device(visits_list: [Visits]) -> [Detections]:
    durations = lambda V: list(map(lambda v: last(v) - first(v), V))
    return map(star(to_argn(durations, n=1)), visits_list)


visits_durations_by_device :: {Device : [Visit]} -> {Device : [Time]}
visits_durations_by_device visits_by_device =
    visit_duration = \v -> (last v) - (first v)
    map_values (\V -> map visit_duration V) visits_by_device
    map_values \(map visit_duration ~) visits_by_device


visits_durations_by_device :: {Device : [Visit]} -> {Device : [Time]} =
    map_values (map (\[first, ... , last] -> first - last))


sum = a b -> a + b

map (x -> sum 3 x) [1, 2, 3]

map sum 3 [1, 2, 3]

map (sum 3 ~) [1, 2, 3]

map {sum 3 ~} [1, 2, 3]




function visits_durations_by_device
         visits_by_device::{Device: [Visit]} -> {Device: [Time]} = {
    visit_duration = \visit => last visit - first visit
    map (\visits => map visit_duration visits) visits_by_device
}


function visits_durations_by_device
         visits_by_device::{Device: [Visit]} -> {Device: [Time]} =
    visit_duration = \visit => last visit - first visit
    map (\visits => map visit_duration visits) visits_by_device
end

function visits_durations_by_device
         visits_by_device::{Device: [Visit]} -> {Device: [Time]} = {
    visit_duration = \visit => last visit - first visit
    map (\visits => map visit_duration visits) visits_by_device
}