sjoerdvisscher’s gists

sjoerdvisscher / Univ.hs

Last active January 14, 2025 14:27

Universal properties with plain Control.Category

	{-# LANGUAGE PolyKinds #-}
	{-# LANGUAGE TypeFamilies #-}
	{-# LANGUAGE TypeOperators #-}
	{-# LANGUAGE FlexibleContexts #-}
	{-# LANGUAGE MultiParamTypeClasses #-}
	{-# LANGUAGE RankNTypes #-}
	{-# LANGUAGE FlexibleInstances #-}
	{-# LANGUAGE StandaloneKindSignatures #-}
	{-# LANGUAGE GADTs #-}
	{-# LANGUAGE UndecidableInstances #-}

sjoerdvisscher / Endofunctors.hs

Last active August 11, 2025 12:27

Another go at implementing polynomial functors a la David Spivak

	{-# LANGUAGE GHC2021, GADTs, DataKinds #-}
	{-# LANGUAGE TypeData #-}
	module Endofunctors where

	import Control.Comonad (Comonad(..))
	import Control.Comonad.Cofree (Cofree(..))
	import Control.Monad (join, ap, void)
	import Control.Monad.Free (Free(..))
	import Data.Bifunctor (first, second, bimap)
	import Data.Functor.Day

ant-arctica / LinearLogic.hs

Last active July 3, 2023 13:22

Implementing linear logic (double negation, ...) in linear haskell using linear-base

	{-# LANGUAGE BlockArguments #-}
	{-# LANGUAGE LambdaCase #-}
	{-# LANGUAGE LinearTypes #-}
	{-# LANGUAGE OverloadedRecordDot #-}
	{-# LANGUAGE NoImplicitPrelude #-}

	-- Quick demonstration that linear-base is enough to implement linear logic

	import Data.Array.Destination
	import Data.Array.Polarized.Pull

basic-calculus / onekappa.hs

Last active March 29, 2021 08:41

One object kappa/zeta calculus, kind of like reflexive objects but also weird

	{-# LANGUAGE RankNTypes #-}
	{-# LANGUAGE FlexibleInstances #-}
	{-# LANGUAGE QuantifiedConstraints #-}
	import Prelude hiding (id, (.))
	import Control.Category
	import Control.Monad.State hiding (lift)

	class Category k => Terminal k where
	term :: k a ()

marcosh / NamedTypeclass.hs

Last active August 17, 2020 05:49

	{-# LANGUAGE AllowAmbiguousTypes #-}
	{-# LANGUAGE MultiParamTypeClasses #-}
	{-# LANGUAGE FlexibleInstances #-}
	{-# LANGUAGE ScopedTypeVariables #-}
	{-# LANGUAGE TypeApplications #-}

	module NamedTypeclass where

	import Prelude hiding (Monoid, mempty, (<>))

sjoerdvisscher / laws.hs

Last active July 14, 2025 18:14

First class checkable laws using the free-functors package

tomlokhorst / Optional+Unwrap.swift

Last active December 26, 2017 19:50

Unwrap multiple optionals in Swift 1.0

	func unwrap<T1, T2>(optional1: T1?, optional2: T2?) -> (T1, T2)? {
	switch (optional1, optional2) {
	case let (.Some(value1), .Some(value2)):
	return (value1, value2)
	default:
	return nil
	}
	}

	func unwrap<T1, T2, T3>(optional1: T1?, optional2: T2?, optional3: T3?) -> (T1, T2, T3)? {

landonf / toy-hlist.swift

Last active August 29, 2015 14:02

	func main () {
	let typedHeterogeneousList = true =+= "Hello" =+= 1 =+= HNil()

	let first: Bool = typedHeterogeneousList.head()
	let second: String = typedHeterogeneousList.tail().head()
	let third: Int = typedHeterogeneousList.tail().tail().head()
	}

	protocol HList {
	typealias Head

sjoerdvisscher / adjointFold.hs

Last active January 8, 2025 11:56

Adjoint folds

	-- http://www.cs.ox.ac.uk/ralf.hinze/SSGIP10/AdjointFolds.pdf
	-- http://www.cs.ox.ac.uk/ralf.hinze/publications/SCP-78-11.pdf
	-- https://www.cs.ox.ac.uk/people/nicolas.wu/papers/URS.pdf

	{-# LANGUAGE
	MultiParamTypeClasses
	, FunctionalDependencies
	, GADTs
	, PolyKinds
	, DataKinds

sebastiaanvisser / g1.hs

Created May 29, 2013 08:36

Composing algebras using Arrow and Applicative.

	{-# LANGUAGE GADTs, TypeOperators, TupleSections #-}
	module Generics.Algebra where

	import Control.Category
	import Control.Arrow
	import Control.Applicative
	import Prelude hiding ((.), id)

	import Generics.Combinator

Sjoerd Visscher sjoerdvisscher