elm/exercises/triangle/Triangle.example

module Triangle exposing (..)

import Set


triangleKind : number -> number -> number -> Result String String
triangleKind x y z =
    if x <= 0 || y <= 0 || z <= 0 then
        Err "Invalid lengths"
    else if x + y <= z || x + z <= y || y + z <= x then
        Err "Violates inequality"
    else
        case Set.size (Set.fromList [ x, y, z ]) of
            1 ->
                Ok "equilateral"

            2 ->
                Ok "isosceles"

            _ ->
                Ok "scalene"