jaspervdj

--------------------------------------------------------------------------------
-- Is List or NonEmpty "simpler"?  Neither:

type NonEmpty a = Fix (Compose ((,) a) Maybe)
type List     a = Fix (Compose Maybe ((,) a))

--------------------------------------------------------------------------------

newtype Fix f = Fix {unFix :: f (Fix f)}

gelisam

-- in response to https://twitter.com/chrislpenner/status/1221784005156036608
--
-- The goal is to mimic this Scala code, but in Haskell:
--
-- > "spotify:user:123:playlist:456" match {
-- >   case s"spotify:user:$userId:playlist:$playlistId"
-- >     => ($userId, $playlistId)  // ("123", "456")
-- > }
{-# LANGUAGE DeriveFunctor, LambdaCase, PatternSynonyms, QuasiQuotes, RankNTypes, TemplateHaskell, TypeOperators, ViewPatterns #-}
{-# OPTIONS -Wno-name-shadowing #-}

domenkozar

module Spec where

import Quickstrom
import Data.Foldable (any)
import Data.Maybe (maybe)
import Data.Tuple (Tuple(..))
import Data.String.CodeUnits (contains)
import Data.String.Pattern (Pattern(..))

readyWhen = "body"

domenkozar

{-# OPTIONS_GHC -fno-warn-orphans #-}

module Repl where

import Cachix.Config (readConfig)
import Cachix.Env (setupApp)
import Cachix.Server.Prelude
import qualified Control.Exception.Safe as Safe
import qualified Language.Haskell.Interpreter as Interpreter
import Protolude

robrix

module FoldsAndUnfolds where

import Data.List -- for unfoldr

class Functor f => Recursive f t | t -> f where
  project :: t -> f t

  cata :: (f a -> a) -> t -> a
  cata alg = go where go = alg . fmap go . project

sjoerdvisscher

-- https://icfp21.sigplan.org/details/icfp-2021-papers/21/Calculating-Dependently-Typed-Compilers-Functional-Pearl-
{-# LANGUAGE GADTs, DataKinds, TypeOperators, TypeFamilies, TypeApplications, KindSignatures, ScopedTypeVariables #-}
import Control.Applicative
import Data.Kind
import Data.Type.Equality

type family (a :: Bool) || (b :: Bool) :: Bool where
  'False || b = b
  'True || b = 'True

brendanzab

/-
  A proof of the correctness of an arithmetic expression compiler in Lean 4.

  Ported from [expcompile.v], which is part of Derek Dreyer and Gert Smolka's
  [course material].

  [expcompile.v]: https://www.ps.uni-saarland.de/courses/sem-ws17/expcompile.v
  [course material]: https://courses.ps.uni-saarland.de/sem_ws1718/3/Resources
-/

depp

// Faster solution for:
// http://www.boyter.org/2017/03/golang-solution-faster-equivalent-java-solution/
// With threading.
// g++ -std=c++11 -Wall -Wextra -O3 -pthread

// On my computer (i5-6600K 3.50 GHz 4 cores), takes about ~160 ms after the CPU
// has warmed up, or ~80 ms if the CPU is cold (due to Turbo Boost).

// How it works: Start by generating a list of losing states -- states where the
// game can end in one turn.  Generate a new list of states by running the game

brendanzab

(** {0 Elaboration with Record Patching and Singleton Types}

    This is a small implementation of a dependently typed language with
    dependent record types, with some additional features intended to make it
    more convenient to use records as first-class modules. It was originally
    ported from {{: https://gist.github.com/mb64/04315edd1a8b1b2c2e5bd38071ff66b5}
    a gist by mb64}.

    The type system is implemented in terms of an ‘elaborator’, which type
    checks and tanslates a user-friendly surface language into a simpler and

paf31

## Principal type-schemes for functional programs

**Luis Damas and Robin Milner, POPL '82**

> module W where

> import Data.List
> import Data.Maybe
> import Data.Function