Jonas Adler jadlr

jadlr / ListPermutations.hs

Last active February 20, 2016 23:09

Permutations of a certain length of a list

	module ListPermutations where

	listPermutations :: Integer => [a] -> b -> [[a]]
	listPermutations l n = snd $ permutate l n
	where permutate :: Integer => [a] -> b -> ([[a]], [[a]])
	permutate [] _ = ([[]], [])
	permutate (x:xs) n = let (pt, acc) = permutate xs n in permutateInner x pt pt acc n
	where permutateInner :: Integer => a -> [[a]] -> [[a]] -> [[a]] -> b -> ([[a]], [[a]])
	permutateInner _ [] pt acc _ = (pt, acc)
	permutateInner h (x:xs) pt acc n

jadlr / ListPermutations.ex

Last active February 22, 2016 11:19

Permutations of a certain length of a list in elixir (v2)

	defmodule ListPermutations do

	def list_permutations(_, 0), do: [[]]
	def list_permutations([], _), do: []
	def list_permutations([h\|t], n), do: Enum.map(list_permutations(t, n-1), fn(l) -> [h\|l] end) ++ list_permutations(t, n)

	end

jadlr / ListPermutations.hs

Last active February 22, 2016 11:06

Permutations of a certain length of a list in haskell (v2)

	module ListPermutations where

	listPermutations :: [a] -> Integer -> [[a]]
	listPermutations _ 0 = [[]]
	listPermutations [] _ = []
	listPermutations (x:xs) n = fmap (x:) (listPermutations xs (n - 1)) ++ listPermutations xs n

jadlr / RateLimiter.scala

Created February 29, 2016 17:06

Reusable rate limiter for akka streams

	import akka.stream.FlowShape
	import akka.stream.scaladsl.{Flow, GraphDSL, Source, Zip}

	import scala.concurrent.duration.FiniteDuration

	object RateLimiter {

	private def rateLimiter[A](rate: FiniteDuration) = {

	case object Tick

jadlr / LeftPad.hs

Last active March 24, 2016 19:42

The Left Pad Chaos (http://www.theregister.co.uk/2016/03/23/npm_left_pad_chaos/)

	module LeftPad where

	leftPad :: Int -> Char -> String -> String
	leftPad n c x
	\| n > length x = leftPad n c (c : x)
	\| otherwise = x

jadlr / FizzBuzz.hs

Last active April 6, 2016 09:15

fizzbuzz in haskell

	{-# LANGUAGE ParallelListComp #-}

	module FizzBuzz where

	-- https://en.wikipedia.org/wiki/Fizz_buzz

	fizzBuzz :: [String]
	fizzBuzz = take 100 $ go 1
	where go n
	\| n `mod` 15 == 0 = "fizzbuzz" : go (n + 1)

jadlr / Repdigit.hs

Created July 19, 2016 20:24

Repdigit sequence calculation in haskell

	module Repdigit where
	-- https://oeis.org/A010785

	repdigit :: Integer -> Integer
	repdigit n = (n - 9 * floor ((fromInteger n - 1) / 9)) * (10 ^ floor ((fromInteger n + 8) / 9) - 1) `quot` 9

	repdigits :: [Integer]
	repdigits = go 0
	where go n = repdigit n : go (n + 1)

jadlr / pushbutton.ex

Last active November 14, 2023 14:51

`gen_statem` example rewritten to elixir (http://erlang.org/doc/design_principles/statem.html)

	defmodule PushButton do
	@behaviour :gen_statem

	@name :pushbutton_statem

	# Client API

	def start do
	:gen_statem.start({:local,@name}, __MODULE__, [], [])
	end

jadlr / pushbutton_handle_events.ex

Created December 9, 2016 13:19

`gen_statem` example rewritten in elixir using only handle_event functions

	defmodule PushButtonHandleEvents do
	@behaviour :gen_statem

	@name :pushbutton_statem

	# Client API

	def start do
	:gen_statem.start({:local,@name}, __MODULE__, [], [])
	end

jadlr / Max.scala

Created May 10, 2017 08:22

Slowly relearning Scala syntax

	import java.util.NoSuchElementException

	import cats._
	import cats.implicits._

	import scala.annotation.tailrec

	object Max extends App {

	def maximum[A : Order](list: List[A]): A = list match {