bitemyapp

Typing Haskell in Haskell

MARK P. JONES

Pacific Software Research Center

Department of Computer Science and Engineering

Oregon Graduate Institute of Science and Technology

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data Query     = Query
data SomeObj   = SomeObj
data IoOnlyObj = IoOnlyObj
data Err       = Err

-- There's a decoder function that makes some object from String
decodeFn :: String -> Either Err SomeObj
decodeFn = undefined

-- There's a query, that runs against DB and returns array of strings

bitemyapp

Austin Haskell

Next Talk

• Scotty / persistent / monad transformers
• GTK

Following Talk

• ghc-mod

bitemyapp

Give me back my sanity

One of the many things I do for my group at work is to take care of automating as many things as possible. It usually brings me a lot of satisfaction, mostly because I get a kick out of making people's lives easier.

But sometimes, maybe too often, I end up in drawn-out struggles with machines and programs. And sometimes, these struggles bring me to the edge of despair, so much so that I regularly consider living on a computer-less island growing vegetables for a living.

This is the story of how I had to install Pandoc in a CentOS 6 Docker container. But more generally, this is the story of how I think computing is inherently broken, how programmers (myself included) tend to think that their way is the way, how we're ultimately replicating what most of us think is wrong with society, building upon layers and layers of (best-case scenario) obscure and/or weak foundations.

*I would like to extend my gratitude to Google, StackOverflow, GitHub issues but mostly, the people who make the

bitemyapp

-- to watch:   telnet localhost 8887
-- to stream:  script -f >( (echo hello streamname; cat -) | nc localhost 8888 > /dev/null )

{-# LANGUAGE OverloadedStrings #-}
module Fcast where

import Control.Concurrent
import Control.Concurrent.STM
import Control.Monad
import Control.Monad.Fix

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{-# LANGUAGE InstanceSigs, OverloadedStrings #-}

module Text.Parser.Selmer where

import           Control.Applicative
import           Data.Char           (isAlpha)
import           Data.Map.Lazy       (Map)
import qualified Data.Map.Lazy       as M
import           Data.Maybe          (fromMaybe)
import           Data.Monoid

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{-# LANGUAGE GADTs, DataKinds, KindSignatures, TypeOperators, TypeFamilies, 
             MultiParamTypeClasses, FlexibleInstances, PolyKinds, FlexibleContexts,
             UndecidableInstances, ConstraintKinds, OverlappingInstances, ScopedTypeVariables #-}

import GHC.TypeLits
import Data.Type.Bool
import Data.Type.Equality
import Data.Proxy
import Control.Applicative ((<$>), (<*>))
import Data.Maybe (catMaybes)

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# This template will give you a prompt with:
#    - ghc
#    - cabal
#    - ghc-mod
#    - the libraries: free, mtl, transformers
#
# to run: nix-shell haskell-project.nix
#
# to specify specific version of haskell, you can: 
#     nix-shell --arg haskellPackages 'with import <nixpkgs> {}; haskellPackages_ghc783_profiling'

bitemyapp

using this Aeson example:

do result <- decode "{\"name\":\"Dave\",\"age\":2}"
      flip parseMaybe result $ \obj -> do
        age <- obj .: "age"
        name <- obj .: "name"
        return (name ++ ": " ++ show (age*2))

Just "Dave: 4"

bitemyapp

import Control.Exception
import Control.Monad
import Control.Monad.IO.Class
import Data.ByteString.Lazy (ByteString)
import Data.ByteString.Lazy.UTF8 (toString)
import Data.Function
import Data.Enumerator
import Data.List
import Data.Maybe