Pitometsu

Yan Shkurinskiy, [18/4/22 8:41 AM]
foo :: Int -> Int
foo x = map fib [0..] !! x
  where
    fib 0 = 1
    fib 1 = 1
    fib n = foo (n-2) + foo (n-1)

foo :: Int -> Int
foo = (map fib [0..] !!)

Pitometsu

#! /usr/bin/env nix-shell
#! nix-shell --show-trace --pure -Q -i "runghc --ghc-arg=-main-is --ghc-arg=Solution.main" -p "ghc.withPackages (pkgs: with pkgs; [ either text ])" -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/cf7475d2061ac3ada4b226571a4a1bb91420b578.tar.gz

-- You'll need nix to automatically download the dependencies:
-- `{ curl https://nixos.org/nix/install | sh ; } && . ~/.nix-profile/etc/profile.d/nix.sh`

{-# LANGUAGE OverloadedStrings
  , PatternSynonyms #-}

import Prelude hiding (lookup)

Pitometsu

let
  channel = with builtins; fromJSON
    (readFile ./lock);
in fetchTarball {
  url = "https://github.com/NixOS/nixpkgs-channels/archive/" +
        "${channel.rev}.tar.gz";
  inherit (channel) sha256;
}

Pitometsu

• Algorithm Design with Haskell
• Beginning Haskell: A Project-Based Approach
• Developing Web Apps with Haskell and Yesod
• Functional Design and Architecture
• Get Programming with Haskell
• Haskell Book
• Haskell Cookbook
• Haskell Data Analysis Cookbook
• Haskell Design Patterns
• Haskell from the Very Beginning

Pitometsu

import static java.lang.System.*;

import java.util.function.BiFunction;
import java.util.function.Function;

// Implementation of a pseudo-GADT in Java, translating the examples from
// http://www.cs.ox.ac.uk/ralf.hinze/publications/With.pdf
// The technique presented below is, in fact, just an encoding of a normal Algebraic Data Type
// using a variation of the visitor pattern + the application of the Yoneda lemma to make it
// isomorphic to the targeted 'GADT'.

Pitometsu

{
  "keymap": [
    {
      "keyCode": 30,
      "label": "1",
      "extraLabel": "!"
    },
    {
      "keyCode": 31,
      "label": "2",

Pitometsu

{
  "keymap": [
    {
      "keyCode": 2079,
      "label": "@"
    },
    {
      "keyCode": 2078,
      "label": "!"
    },

Pitometsu

{-# LANGUAGE DataKinds #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE PolyKinds #-}

import Data.Kind (Constraint)

type family All (c :: k -> Constraint) ts :: Constraint where All c '[] = (); All c (t:ts) = (c t, All c ts)

Pitometsu

{-# LANGUAGE DataKinds #-}
{-# LANGUAGE KindSignatures #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE OverloadedLabels #-}
{-# LANGUAGE BlockArguments #-}
{-# LANGUAGE UnicodeSyntax #-}

Pitometsu

type _ num =
  | Zero : zero num
  | Succ : ('a num) -> 'a plus num
and _ plus = Plus : 'a num -> 'a plus
and zero = [ ]
;;
type _ even =
  | Even_0 : zero num even
  | Even_S : 'a num odd -> 'a plus num even
and _ odd =