christiantakle

// Classic Javascript
function fib(n) {
  if(n === 0) { return 0 }
  if(n === 1) { return 1 }
  return fib(n-1) + fib(n-2)}

// Non-auto-curry
const mkCases = // :: Object Functions -> a -> b
  cases => key =>
    (cases[key]? cases[key] : cases["_"])(key)

christiantakle

// Orignal ------------------------------------------------------------
var isFancy = true;

var fancy = document.querySelector("#commentsbtn");
fancy.addEventListener("click", function(e){
  if (isFancy) {
    document.body.classList.remove("fancy-comments");
    isFancy = false;
  }
  else {

christiantakle

Direct links to free Springer maths books (pdf versions)

duplicates = multiple editions

A Classical Introduction to Modern Number Theory,Kenneth IrelandMichael Rosen

A Classical Introduction to Modern Number Theory,Kenneth IrelandMichael Rosen

A Course in Arithmetic,Jean-Pierre Serre

christiantakle

//-- Sum --------------------------------------------------------------
let
  identity = 0,
  mappend  = (x,y) => x + y, // +
  concatSum =
    xs => xs.reduce(mappend, identity)

concatSum([1,2,3,4,5]) // => 15

//-- Product ----------------------------------------------------------

christiantakle

{-# LANGUAGE ForeignFunctionInterface, JavaScriptFFI #-}
import Reflex.Dom
import Data.Monoid
import GHCJS.Types
import GHCJS.Foreign
import GHCJS.DOM.Element
import GHCJS.DOM.Types
import Control.Monad.IO.Class

newtype LeafletMap = LeafletMap { unLeafletMap :: JSRef LeafletMap }

christiantakle

{-# LANGUAGE DeriveFunctor #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE StandaloneDeriving #-}
{-# LANGUAGE UndecidableInstances #-}

import Prelude hiding (succ)

newtype Fix f = Fix (f (Fix f))

deriving instance (Show (f (Fix f))) => Show (Fix f)

christiantakle

-- old ----------------------------------------------------------------
mkGraphMeta (start,end) (aggregated,timeSeriesWithColor) =
  (aggregated,) $ fromMaybe (Nothing,[]) $ case second unTimeSeries <$> (timeSeriesWithColor :: [(String,TimeSeries)]) of
    []  -> Nothing
    xss -> do
      minMax@(vMin,vMax) <- getMinMax $ snd <$> (xss :: [(String,[(UTCTime,Double)])])
      let
        tw = end `diffUTCTime` start
        fx = fromIntegral pWidth / tw
        ph = fromIntegral pHeight

christiantakle

Postgres Cheat Sheet
Source: Postgresql Documentation

### shell commands
	
	creatuser <user>
	deletesuer <user>
	createdb -O <user> -E utf8 -T <template> <db_name>
	dropdb <db_name>

christiantakle

{-# LANGUAGE TupleSections #-}

import Control.Lens

data Expr
  = Var String
  | App Expr Expr
  | Lam String Expr
  deriving Show

christiantakle

const
  whenDivisibleBy = (x, t, f) => n => (n % x == 0 ? t : f),
  fizz = whenDivisibleBy(3, 'Fizz', ''),
  buzz = whenDivisibleBy(5, 'Buzz', ''),
  fizzBuzz = n => fizz(n) + buzz(n) || String(n);

//Array(...Array(100)).map((_,x) => fizzBuzz(x+1))