djspiewak

How to GPG as a Scala OSS Maintainer

tl;dr Generate a GPG key pair (exercising appropriate paranoia). Send it to key servers. Create a Keybase account with the public part of that key. Use your keypair to sign git tags and SBT artifacts.

GPG is probably one of the least understood day-to-day pieces of software in the modern developer's toolshed. It's certainly the least understood of the important pieces of software (literally no one cares that you can't remember grep's regex variant), and this is a testament to the mightily terrible user interface it exposes to its otherwise extremely simple functionality. It's almost like cryptographers think that part of the security comes from the fact that bad guys can't figure it out any more than the good guys can.

Anyway, GPG is important for open source in particular because of one specific feature of public/private key cryptography: signing. Any published software should be signed by the developer (or company) who published it. Ideally, consu

jdegoes

module Main where
  import Debug.Trace
  import Halogen

  main = do
    trace "Hello sailor!"

module Halogen where
  import Control.Monad.State.Trans
  import Control.Monad.State.Class

paf31

module Main where

import qualified Prelude as P
import Debug.Trace

class Arithmetic lang where
  (+) :: lang Number -> lang Number -> lang Number
  (-) :: lang Number -> lang Number -> lang Number
  (*) :: lang Number -> lang Number -> lang Number
  (/) :: lang Number -> lang Number -> lang Number

pchiusano

-- A port of: http://semantic-domain.blogspot.com/2015/03/abstract-binding-trees.html

{-# LANGUAGE DeriveFunctor #-}

module ABT where

import qualified Data.Foldable as Foldable
import Data.Foldable (Foldable)
import Data.Set (Set)
import qualified Data.Set as Set

natefaubion

test = map ((*) 2) >>> filter ((>) 15) >>> drop 3 >>> map show
src1 = [10, 9, 8, 7, 6, 5, 4, 3, 2, 1]
src2 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

res1 = transduce' test src1 :: [String]
res2 = transduce' test src2 :: List String

djspiewak

package com.rr.experiment

import org.specs2.ScalaCheck
import org.specs2.mutable._

import org.scalacheck._

import scalaz._

import scodec._

pchiusano

This is material to go along with a 2014 Boston Haskell talk.

We are going to look at a series of type signatures in Haskell and explore how parametricity (or lack thereof) lets us constrain what a function is allowed to do.

Let's start with a decidedly non-generic function signature. What are the possible implementations of this function which typecheck?

wrangle :: Int -> Int

runarorama

sealed trait Interact[A]

case class Ask(prompt: String)
  extends Interact[String]

case class Tell(msg: String)
  extends Interact[Unit]

trait Monad[M[_]] {
  def pure[A](a: A): M[A]

gelisam

-- in reply to http://www.reddit.com/r/haskell/comments/21mja6/make_lllegal_state_transitions_unrepresentable/
-- 
-- We implement a tiny language with three commands: Open, Close, and Get.
-- The first Get after an Open returns 1, the second Get returns 2, and so on.
-- 
-- Get is only valid while the state is open, and
-- Open must always be matched by a Close.
-- We enforce both restrictions via the type system.
-- 
-- There are two valid states: Opened and Closed.

sebastiaanvisser

-- | Echo: a small experimental library for functional reactive programming.

{-# LANGUAGE
    GADTs
  , GeneralizedNewtypeDeriving
  , TemplateHaskell
  , RecursiveDo
  , MagicHash
  , UnboxedTuples
  #-}