multisort.ls

{reverse, sum, empty, all, fold, concat-map, flatten, span, Obj, sort-by, head} = require 'prelude-ls'

# [[String]] -> Bool
in-order = (xss) -> all (-> it.length == 1), xss

# [[String] -> Data -> [[String]]] -> Data -> [String] -> [[String]]
order-by-one = (fs, d, xs) -->
  | xs.length < 2 => [xs]
  | otherwise =>
    fold ((ys, f) -> if ys.length == 1 then f(ys[0], d) else ys), [xs], fs

# [[String] -> Data -> [[String]]] -> [[String]] -> Data  -> [[String]]
order-by-many = (fs, xss, d) ->
  let yss = concat-map order-by-one(fs, d), xss
    switch
    | yss.length == xss.length => flatten yss
    | in-order yss => flatten yss
    | otherwise => order-by-many fs, yss, d

# [[String] -> Data -> [[String]]] -> [String] -> Data -> [String]
multisort = (fs, xs, d) -> order-by-many fs, [xs], d