# Syntax Hints (OCaml -> Elm)

> Source: <https://gist.github.com/evancz/17cfb9ff531f839f82f050d05cd725b2>
> Published: 2022-04-19 21:21:42+00:00

ocaml.elm

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module Hints exposing (..)

import List

import Html exposing (..)

import Html.Attributes as A

{-----------------------------------------------------------

      SYNTAX HINTS (OCaml -> Elm)

------------------------------------------------------------

  EXPRESSIONS

    | OCaml             | Elm                |

    |-------------------|--------------------|

    | "hello" ^ name    |  "hello" ++ name   |

    |  x + 1            |   x + 1            |

    |  x +. 1.0         |   x + 1            |

    |  ~-3              |   -3               |

    |  x <> 0           |   x /= 0           |

    |  [1;2;3]          |   [1,2,3]          |

  TYPES

    | OCaml             | Elm                |

    |-------------------|--------------------|

    | int               |  Int               |

    | string            |  String            |

    | 'a list           |  List a            |

    | 'a option         |  Maybe a           |

    | (int * int)       |  (Int, Int)        |

-----------------------------------------------------------}

{- FUNCTIONS -----------------------------------------------

let square (x : int) : int =

  x * x

-----------------------------------------------------------}

square : Int -> Int

square x =

  x * x

{- RECURSIVE FUNCTIONS -------------------------------------

let rec map (func : 'a -> 'b) (list : 'a list) : 'b list =

  match list with

  | []    -> []

  | x::xs -> func x :: map func xs

-----------------------------------------------------------}

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

map func list =

  case list of

    []    -> []

    x::xs -> func x :: map func xs

{- TYPE ALIASES --------------------------------------------

type person = { name : string; id : int }

-----------------------------------------------------------}

type alias Person = { name : String, id : Int }

{- ADTs ----------------------------------------------------

type color_label =

  | Red

  | Orange

  | Yellow

  | Green

  | Blue

  | Indigo

  | Violet

type color =

  | Simple of color_label

  | RGB of int * int * int

-----------------------------------------------------------}

type ColorLabel

  = Red

  | Orange

  | Yellow

  | Green

  | Blue

  | Indigo

  | Violet

type Color

  = Simple ColorLabel

  | RGB Int Int Int

{- More ADTs -----------------------------------------------

type 'a option =

  | None

  | Some of 'a

type 'a bintree =

  | Leaf

  | Node of 'a * 'a bintree * 'a bintree

-----------------------------------------------------------}

type Maybe a

  = Nothing

  | Just a

type Tree a

  = Leaf

  | Node a (Tree a) (Tree a)