tonymorris

#include <tr1/type_traits>
#include <iostream>
#include <vector>
#include <algorithm>

// (* -> *) -> Constraint
template<template <typename> class T>
class Functor {
public:
  template <typename A, typename B>

tonymorris

import           Control.Applicative
import           Control.Concurrent  (forkIO, newEmptyMVar, putMVar, takeMVar)
import           Control.Monad
import           Control.Monad.Trans.Class
import           Control.Monad.IO.Class
import           System.Command

newtype Cmd m a = Cmd { runCmd :: m (Either (Int, String) a) }

cmd :: MonadIO m => FilePath -> [String] -> String -> Cmd m String

tonymorris

There seems to be a lot of confusion around Effects and IO. I wanted to collect a set of questions and answers, and explanations of common misconceptions.

1. What is an Effect?

Effects come in many different shapes. In terms of monadic effects, there are different shapes again. For example, List (non-determinism), State, IO, Cont.

2. What is a Side Effect?

An effect that is occurs to the side of the effect you are otherwise running within. In most standard environments, this is an IO effect that occurs outside of the otherwise effectful environment.

tonymorris

name:               package
version:            0.0.1
license:            BSD3
license-File:       LICENCE
category:           Development
cabal-version:      >= 1.10
build-type:         Custom

flag                small_base
  description:      Choose the new, split-up base package.

tonymorris

// see https://github.com/gseitz/Lensed

case class CoState[A, B](put: A => B, pos: A)

object CoState {
  type Store[A, B] = CoState[A, B]
}

// fused get/set
case class Lens[A, B](lens: A => CoState[B, A]) {