piq9117

SPC
    SPC: find file
    , switch buffer
    . browse files
    : MX
    ; EX
    < switch buffer
    ` eval
    u universal arg
    x pop up scratch

piq9117

Phantom types in ReasonML

Introduction

"A phantom type is a parametrised type whose parameters do not all appear on the right-hand side of its definition..." Haskell Wiki, PhantomType

The following write-up is intended as an introduction into using phantom types in ReasonML.

Taking a look at the above definition from the Haskell wiki, it states that phantom types are parametrised types where not all parameters appear on the right-hand side. Let's try to see if we can implement a similar example as in said wiki.

piq9117

module type FUNCTOR = sig
    type 'v f
    val map : ('a -> 'b) -> 'a f -> 'b f
end

module type MONAD = sig
    type 'v f
    val map : ('a -> 'b) -> 'a f -> 'b f
    val pure : 'a -> 'a f
    val join : ('a f) f -> 'a f

piq9117

module type FUNCTOR = sig
    type 'v f
    val map : ('a -> 'b) -> 'a f -> 'b f
end

module type MONAD = sig
    type 'v f
    val map : ('a -> 'b) -> 'a f -> 'b f
    val pure : 'a -> 'a f
    val join : ('a f) f -> 'a f

piq9117

'use strict';

/*****************NATIVE forEACH*********************/

Array.prototype.myEach = function(callback) {
    for (var i = 0; i < this.length; i++)
        callback(this[i], i, this);
};

//tests

piq9117

{-# LANGUAGE RecordWildCards, Arrows #-}

import Numeric
import Data.Char

import Control.Monad
import Data.Monoid ((<>))
import Data.List (nub, sort, reverse)

data RepeatBounds = RB

piq9117

Note: This guide applies to the project created by quasar-cli.

First install typescript and ts-loaderpackages in your project.

npm i -D typescript ts-loader

Then modified the quasar.conf.js file in your project:

piq9117

import Control.Monad

-------------------------------------------------------------------------------
-- State Monad Implementation
-------------------------------------------------------------------------------

newtype State s a = State { runState :: s -> (a,s) }

instance Monad (State s) where
  return a = State $ \s -> (a, s)

piq9117

SPC s c remove highlight

**** Files manipulations key bindings
Files manipulation commands (start with ~f~):

| Key Binding | Description                                                    |
|-------------+----------------------------------------------------------------|
| ~SPC f c~   | copy current file to a different location                      |
| ~SPC f C d~ | convert file from unix to dos encoding                         |
| ~SPC f C u~ | convert file from dos to unix encoding                         |

piq9117

const I = x => x;
const K = x => y => x;
const A = f => x => f(x);
const T = x => f => f(x);
const W = f => x => f(x)(x);
const C = f => y => x => f(x)(y);
const B = f => g => x => f(g(x));
const S = f => g => x => f(x)(g(x));
const P = f => g => x => y => f(g(x))(g(y));
const Y = f => (g => g(g))(g => f(x => g(g)(x)));