List.Cartesian

Cartesian product version of List andMap and mapN functions.

This module's functions behave differently from the "common" ones in elm/core and elm-community/list-extra in that instead of zipping they will run through all combinations of the lists you provide:

List.Cartesian.map2 (+) [ 1, 2 ] [ 100, 200, 300 ]
--> [ 101, 201, 301, 102, 202, 302 ]

Compare that with the default zipping behaviour:

List.map2 (+) [ 1, 2 ] [ 100, 200, 300 ]
--> [ 101, 202 ]

andMap : List a -> List (a -> b) -> List b

A building block for arbitrary mapN functions. See map5 for more info.

Note that andMap allows you to do stuff you might not realize is possible with map2 etc.:

[ (+), (*) ]
    |> List.Cartesian.andMap [ 1, 2 ]
    |> List.Cartesian.andMap [ 90, 93, 96 ]
--> [ 91, 94, 97, 92, 95, 98, 90, 93, 96, 180, 186, 192 ]

map2 : (a -> b -> c) -> List a -> List b -> List c

Equivalent to

[ fn ]
    |> List.Cartesian.andMap xs
    |> List.Cartesian.andMap ys

Also equivalent to List.Extra.lift2.

List.Cartesian.map2 (*) [ 10, 100 ] [ 1, 2, 3 ]
--> [ 10, 20, 30, 100, 200, 300 ]

map3 : (a -> b -> c -> d) -> List a -> List b -> List c -> List d

Equivalent to

[ fn ]
    |> List.Cartesian.andMap xs
    |> List.Cartesian.andMap ys
    |> List.Cartesian.andMap zs

Also equivalent to List.Extra.lift3.

map4 : (a -> b -> c -> d -> e) -> List a -> List b -> List c -> List d -> List e

Equivalent to

[ fn ]
    |> List.Cartesian.andMap xs
    |> List.Cartesian.andMap ys
    |> List.Cartesian.andMap zs
    |> List.Cartesian.andMap ws

Also equivalent to List.Extra.lift4.

map5 :

(a -> b -> c -> d -> e -> f)

-> List a

-> List b

-> List c

-> List d

-> List e

-> List f

Equivalent to

[ fn ]
    |> List.Cartesian.andMap xs
    |> List.Cartesian.andMap ys
    |> List.Cartesian.andMap zs
    |> List.Cartesian.andMap ws
    |> List.Cartesian.andMap vs

In case you're looking for map6 etc., you can use the above andMap pattern to map as many lists you want.

Janiczek/elm-list-cartesian/1.0.2

List.Cartesian

Modules