tonymorris

module Every where

import Control.Lens
import Control.Monad.Fix

-- |
--
-- >>> everyN 2 []
-- []
--

tonymorris

import System.Environment
import System.IO
import Control.Monad (when)

matchGlob :: String -> String -> Bool
matchGlob = undefined

main :: IO ()
main = do
  args <- getArgs

tonymorris

Parametricity, or Theorems for Free

Say more by saying less. Learn how parametric types, when used in conjunction with an adequately strong type system, help the programmer comprehend code by invalidating candidate programs. Parametricity helps the programmer by enabling deduction of theories about what a program cannot do, sometimes to the point of leaving no ambiguity.

tonymorris

Response to https://peerj.com/preprints/826v1/

1.

The method is dubious with respect to the conclusion.

The researchers do not analyse the code using any formal
or even established reliable methods. Instead, the metric that is used is "look
to see if some *detected* bug, which was fixed *post-release*.

tonymorris

• mount indicators
• install air filter
• install rear rack
• install braided fuel line
• install headlight protector
• mount spotlights
• install windscreen
• change oil filters
• install foam air filter
• adjust rear shock

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]) {

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

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

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

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

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