polytypic

;; Type indexed values in 1ML
;;
;; This is a very simple experiment at encoding type-indexed values in 1ML.
;;
;; Background:
;;
;;   https://people.mpi-sws.org/~rossberg/1ml/
;;   http://repository.readscheme.org/ftp/papers/zheyang-icfp98.pdf
;;
;; Run as:

polytypic

;; -----------------------------------------------------------------------------

;; Unit type
Unit :> {
  type t;
  one : t;
} = {
  type t = bool;
  one = true;
};

polytypic

let id x => x;
let always x _ => x;
let (>>) f g x => g (f x);
let (<|) f x => f x;

module Option = {
  type t 'a = option 'a;
  let toArray xO => switch xO {
    | None   => [||]
    | Some x => [|x|]

polytypic

import * as R from "ramda"
import React  from "react"

// Rules from http://www.cse.tkk.fi/fi/opinnot/CSE-A1121/English2015/harjoitukset/kierros_2/harj_1/index.html
// Nope, I haven't rigorously checked that I implemented the rules correctly.

const consonantRule =
  R.replace(/([aeiouyäö])([b-df-hj-np-tvwxz]*)([b-df-hj-np-t-tvwxz])([aeiouyäö])/gi,
            "$1$2\xAD$3$4")

polytypic

// So called van Laarhoven lenses, named after their discoverer, have a number
// of nice properties as explained by Russell O'Connor:
//
//   http://r6.ca/blog/20120623T104901Z.html
//
// Unfortunately their typing (in Haskell)
//
//   type Lens s t a b = forall f. Functor f => (a -> f b) -> (s -> f t)
//
// seems to be well outside of what can be achieved in F#.