Joomy Korkut joom

Introduction

At DICOM Grid, we recently made the decision to use Haskell for some of our newer projects, mostly small, independent web services. This isn't the first time I've had the opportunity to use Haskell at work - I had previously used Haskell to write tools to automate some processes like generation of documentation for TypeScript code - but this is the first time we will be deploying Haskell code into production.

Over the past few months, I have been working on two Haskell services:

A reimplementation of an existing socket.io service, previously written for NodeJS using TypeScript.
A new service, which would interact with third-party components using standard data formats from the medical industry.

I will write here mostly about the first project, since it is a self-contained project which provides a good example of the power of Haskell. Moreover, the proces

Basic unit type:

λ> replTy "()"
() :: ()

Basic functions:

Awesome Electronic and Hardware platform

A curated list of amazingly awesome Electronic and Hardware platform #WoT #IoT #M2M

Awesome Electronic and Hardware platform

	module FizzBuzzC

	%default total

	-- Dependently typed FizzBuzz, constructively

	-- A number is fizzy if it is evenly divisible by 3
	data Fizzy : Nat -> Type where
	ZeroFizzy : Fizzy 0
	Fizz : Fizzy n -> Fizzy (3 + n)

	{-# LANGUAGE GADTs #-}
	module Yolo where

	import System.IO.Unsafe

	class Yolo f where
	yolo :: f a -> a

	instance Yolo Maybe where
	yolo (Just x) = x

	// REQUIRES:
	// moment.js - http://momentjs.com/

	// USAGE:
	// {{ someDate \| moment: [any moment function] : [param1] : [param2] : [param n]

	// EXAMPLES:
	// {{ someDate \| moment: 'format': 'MMM DD, YYYY' }}
	// {{ someDate \| moment: 'fromNow' }}

	Require Import Coq.Arith.Div2.
	Require Import Coq.Arith.Mult.
	Require Import Coq.Arith.Even.
	Require Import ArithRing.

	Fixpoint triangular (n: nat) :=
	match n with
	\| 0 => 0
	\| S n => (S n) + triangular (n)
	end.

	-- source of `tranpose`: `Applicative programming with effects` by McBride/Paterson

	transpose :: [[a]] -> [[a]]
	transpose [] = repeat []
	transpose (xs : xss) = zipWith (:) xs (transpose xss)

	-- I didn't fully understand this function, so I decided to fully evaluate it by substituion.

	transpose [[1,2,3], [4,5,6]] === zipWith (:) [1,2,3] (transpose [[4,5,6]])
	=== zipWith (:) [1,2,3] (zipWith (:) [4,5,6] (transpose []))

	module reornament

	-- Idris translation of Agda code:
	-- https://gist.github.com/gallais/e507832abc6c91ac7cb9

	-- Which follows Conor McBride's Ornaments paper:
	-- https://personal.cis.strath.ac.uk/conor.mcbride/pub/OAAO/Ornament.pdf

	ListAlg : Type -> Type -> Type
	ListAlg A B = (B, A -> B -> B)

	-- A port of: http://semantic-domain.blogspot.com/2015/03/abstract-binding-trees.html

	{-# LANGUAGE DeriveFunctor #-}

	module ABT where

	import qualified Data.Foldable as Foldable
	import Data.Foldable (Foldable)
	import Data.Set (Set)
	import qualified Data.Set as Set