valyakuttan

-- file: ch19/ParseInt.hs
{-# LANGUAGE GeneralizedNewtypeDeriving #-}

import Data.Char
import Control.Monad
import Control.Monad.Error
import Control.Monad.State
import qualified Data.ByteString.Char8 as B

data ParseError = NumericOverflow

valyakuttan

{-# LANGUAGE GeneralizedNewtypeDeriving #-}

import System.Exit
import System.IO
import Control.Exception (bracket_)
import System.Process (readProcessWithExitCode)
import Control.Monad.Error (MonadError, ErrorT, runErrorT, throwError, lift)
import Control.Monad.IO.Class

newtype Shell a = Shell { runShell :: ErrorT String IO a }

valyakuttan

# before install lens, install zlib development package
sudo apt-get install zlib1g-dev
cabal install lens

valyakuttan

{-

 from http://lukepalmer.wordpress.com/2008/08/10/mindfuck-the-reverse-state-monad/

 also look at https://github.com/luqui/backward-state

-}
module RState where

newtype RState s a = RState { runRState :: s -> (a,s) }

valyakuttan

{-# LANGUAGE FlexibleInstances, MultiParamTypeClasses  #-}

module StateB where

import Control.Monad.State 

newtype StateB s a = StateB {runStateB :: s -> (a,s)}

instance Monad (StateB s) where

valyakuttan

#! /bin/bash

# install ghc-terminfo-dev
sudo apt-get install libghc-terminfo-dev

# install alex from hackage
cabal update; cabal install alex

# install idris from hackage
cabal install idris

valyakuttan

#!/bin/sh

# from http://stackoverflow.com/questions/1471571/how-to-configure-postgresql-for-the-first-time
#
# debian jessie
# PostgreSQL 9.3

sudo apt-get install postgresql postgresql-client

# connect to standard system database template1

valyakuttan

1. In pg_hba.conf file change line
   • local all postgres peer
   • or local all postgres md5
   • to local all postgres trust
2. restart postgreSQL by /etc/init.d/postgresql restart
3. login as postgres by psql -U postgres
4. change password by issuing the query ALTER USER postgres with encrypted password 'secret';
5. undo changes done in step1
6. restart

valyakuttan

import Control.Monad
import Control.Monad.ST
import Data.Array.ST
import Data.Array.Unboxed

primesUpto :: Int -> [Int]
primesUpto n = [p | (p, True) <- assocs $ sieve n]

sieve :: Int -> UArray Int Bool
sieve n = runSTUArray $ do

valyakuttan

import Control.Monad

main :: IO ()
main = forM_ [1..100] $ \n -> do
         let f n = case (n `mod` 2, n `mod` 5) of
                     (0,0) -> "fizzbuzz"
                     (0,_) -> "fizz"
                     (_,0) -> "buzz"
                     _     -> show n
         putStrLn $ f n