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Haskell DB Library Comparison

We will be comparing the following DB libraries:

• HRR
• Opaleye
• Persistent + Esqueleto
• Groundhog
• postgresql-simple (and postgresql-transactional)

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#!/usr/bin/env stack
-- stack --resolver=nightly-2015-07-08 runghc --package=shelly

-- The ExtendedDefaultRules extension gives us an experience similar to
-- @ghci@.  Raw values (1 and 10 below) that implement the 'Num' type 
-- class will be defaulted to 'Int' (specified with the @default@
-- command below).  Raw values (all strings) that implement the
-- 'IsString' typeclass will be defaulted to Text (also specified
-- with the @default@ command below).
--

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dist
cabal-dev
*.o
*.hi
*.chi
*.chs.h
*.dyn_o
*.dyn_hi
.hpc
.hsenv

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{-# LANGUAGE ScopedTypeVariables #-}

-- | This is an explanation of a combination function written in Haskell
-- from http://rosettacode.org/wiki/Combinations#Dynamic_Programming_2

module Main where

-- | Adds a @a@ to the beginning of every list inside the list of lists.
-- However, if the list of lists is just an empty list, return an empty
-- list.

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{-# LANGUAGE Rank2Types #-}

-- This is a small example of where you need to use Rank2Types (or
-- RankNTypes).


-- The 'a' type is being used polymorphically here, but when it
-- is called, it will already be bound (as either an Int or String),
-- so it cannot be used polymorphically.
--

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Haskell Resources

• Learning Haskell
• Learn You a Haskell for Great Good
  • Learn You A Haskell Exercises
• Real World Haskell
• FPComplete's School of Haskell
• Haskell Wikibook
• Write Yourself a Scheme in 48 Hours
• Parallel and Concurrent Programming in Haskell

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#!/usr/bin/env runhaskell -Wall

import Control.Concurrent (threadDelay, forkIO)
import Control.Concurrent.MVar
import Control.Monad (liftM, filterM)
import Data.List (isPrefixOf, (\\))
import HSH.ShellEquivs (glob)
import System.Directory (canonicalizePath, getCurrentDirectory, doesFileExist)
--import System.Environment (getArgs)
import System.FilePath ((</>))