melrief’s gists

melrief / swap.hs

Last active August 29, 2015 13:55

Print swap memory used by each process

	{-# LANGUAGE OverloadedStrings #-}
	import Control.Applicative
	import Control.Exception
	import Control.Monad
	import Data.Char
	import Data.List
	import Data.Maybe
	import Data.ByteString.Char8 (ByteString)
	import qualified Data.ByteString.Char8 as C
	import Prelude hiding (readFile)

melrief / csv.hs

Created November 25, 2013 10:26

Create a list of strings from a CSV line. Requires the DList library installed. Usage example: ghc csv.hs; ./csv 'foo,bar,"foo,bar","foo bar "" foo,,bar",bar'

	import Control.Monad (forM_)
	import qualified Data.DList as DL
	import System.Environment (getArgs,getProgName)
	import System.Exit (exitSuccess)

	data CSVState = OutsideQuote \| InsideQuote \| AfterQuote

	listFromCSV :: String
	→ [String]
	listFromCSV = toResult ∘ foldl parseChar (OutsideQuote,DL.empty,DL.empty)

melrief / 23Tree.hs

Last active December 26, 2015 20:09

23Tree implementation in Haskell (http://en.wikipedia.org/wiki/2-3_tree)

	{-# LANGUAGE InstanceSigs #-}
	module Data.TwoThreeTree where

	import Control.Applicative
	import Data.Foldable
	import Data.Traversable
	import Prelude hiding (foldr)


	data Tree23 k = Leaf

melrief / ViewConvexHull.hs

Created August 31, 2013 22:47

An example of Graphics.Rendering.Chart usage from the haskell chart package (https://github.com/timbod7/haskell-chart/wiki). Calculates and shows the convex hull (http://en.wikipedia.org/wiki/Convex_hull) from a finite list of points using the Graham's scan method (http://en.wikipedia.org/wiki/Graham_scan)

	-- To build just copy this and convexhull.cabal somewhere
	-- and then run cabal build
	--
	-- Usage Example:
	-- > ./dist/build/viewConvexHull/viewConvexHull plot.pdf 1,10 10,5 4,6 7,9 20,1 4,2 5,6 8,2 3,9
	--
	-- this creates a pdf file called plot.pdf with the plot in the current directory
	module Main where

	import Control.Arrow

melrief / GoldenColors.hs

Last active December 20, 2015 14:58

Create a list of very different colors using http://martin.ankerl.com/2009/12/09/how-to-create-random-colors-programmatically/

	import Data.Colour.RGBSpace.HSV (RGB, hsv)

	nextColor :: (RealFrac a) => a -> a -> a -> (RGB a,a)
	nextColor h s v = let h' = (h + golden_ratio_conjugate) % 360
	in (hsv h' s v,h')
	where golden_ratio_conjugate = 222.4922359499622 -- 0.618033988749895 * 360
	dividend % divisor = dividend - divisor *
	(fromIntegral $ floor (dividend/divisor))

	goldenColors :: (RealFrac a) => a -> a -> a -> [RGB a]

melrief / lines.hs

Created July 19, 2013 19:14

Lazily prepend the line number to each line

	import Control.Monad (unless)
	import Prelude hiding (catch)
	import System.IO (isEOF)

	prependLineNums :: Int -> IO ()
	prependLineNums n = isEOF >>= flip unless prependLineNum
	where prependLineNum = getLine >>= putStrLn . (++) (padTo 5 $ show n)
	>> prependLineNums (n+1)
	padTo c s = case c `compare` length s of
	GT -> s ++ replicate (c - length s) ' '

Mario Pastorelli melrief