joshburgess

FreeAp f is a Comonad

While thinking about comonads as spaces and Day convolution, I realized an interesting thing. The free applicative functor generated by a comonad f is also a comonad.

The free applicative can be defined in a few different ways, but I like to define it like this:

data FreeApplicative f a = Pure a | Free (Day f (FreeApplicative f) a)

joshburgess

{-# LANGUAGE GeneralisedNewtypeDeriving #-}

module Data where

type UserName = String

data DataResult = DataResult String
  deriving (Eq, Show)

class Monad m => Cache m where

joshburgess

module Algebra where

import Prelude
import Control.Monad.Eff (Eff)
import Data.Maybe (Maybe(..))


newtype ConsoleAlg f = ConsoleAlg
  { printLn :: String -> f Unit 
  , readLn :: f String

joshburgess

{-# LANGUAGE DefaultSignatures #-}
{-# LANGUAGE FunctionalDependencies #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE UndecidableInstances #-}

import Control.Monad.Trans.Class
import qualified Control.Monad.Trans.State as State
import Control.Monad.Trans.Identity (IdentityT)
import Control.Monad.Trans.Reader (ReaderT)

joshburgess

    let Version = ∀(Version : Type) → ∀(v : Text → Version) → Version

in  let VersionRange =
            ∀(VersionRange : Type)
          → ∀(anyVersion : VersionRange)
          → ∀(noVersion : VersionRange)
          → ∀(thisVersion : Version → VersionRange)
          → ∀(notThisVersion : Version → VersionRange)
          → ∀(laterVersion : Version → VersionRange)
          → ∀(earlierVersion : Version → VersionRange)

joshburgess

(*
  Requirement: higher, ppx_deriving.show
*)

(*
  Lightweight higher-kinded polymorphism
  https://ocamllabs.github.io/higher/lightweight-higher-kinded-polymorphism.pdf
 *)
open Higher

joshburgess

project=$(basename "$(pwd)")

# build dependencies
build_deps="stack build $project --fast --pedantic --dependencies-only --interleaved-output"

# restart on changes in other packages
restarts=$(find ../. -maxdepth 1 -type d \
  -not -name "$project" \
  -not -name .stack-work \
  -not -name . \

joshburgess

{-# language TypeInType #-}

-- | Types which have PureScript equivalents
class ToPursTyCon a where
  toPursTyCon :: Tagged a PursTypeConstructor

  -- | The default instance uses 'G.Generic' and pattern matches on the
  -- type's representation to create a PureScript type.
  default toPursTyCon :: (G.Generic a, GenericToPursTyCon (G.Rep a)) => Tagged a PursTypeConstructor
  toPursTyCon = retag $ genericToPursTyConWith @(G.Rep a) defaultPursTypeOptions

joshburgess

export type Cancel = void | ((k: (r: void) => void) => void)

export const runCancel = (c: Cancel, k: (r: void) => void): void =>
  c ? c(k) : k()

export type Fx<H, A> = (handler: H, k: (a: A) => void) => Cancel
export type Pure<A> = Fx<{}, A>

export const handle = <H0, H1, A>(fx: Fx<H0 & H1, A>, h1: H1): Fx<H0, A> =>
  (h0, k) => fx({ ...h0, ...h1 } as H0 & H1, k)

joshburgess

{-# LANGUAGE OverloadedLabels #-}
{-# LANGUAGE DuplicateRecordFields #-}
{-# LANGUAGE DeriveGeneric #-}
module LensLabels where

import Prelude
import Control.Lens
import Data.Generics.Labels
import GHC.Generics