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"