nvanderw

import Control.Monad
import Control.Monad.Identity (runIdentity)
import Control.Monad.Error
import Control.Monad.State.Lazy

import Data.Maybe (listToMaybe)


-- |Monad transformer which stores a stack internally
type StackT s m = StateT [s] m

nvanderw

import itertools

# Monad instance on a Python iterator, very similar to Haskell's list monad.
# In general, Haskell typeclass instances can be regarded as dictionaries which
# map the implemented function to its implementation. For a good explanation of
# this, see Philip Wadler's "Faith, Evolution, and Programming Languages"
# lecture. What this means for us is that we can write a function whose type
# signature in Haskell would be:
# Monad m => f m
#

nvanderw

import Control.Monad
import Control.Monad.State.Lazy

-- Simple way to get Fibonacci numbers using monad transformers
fibT :: (Monad m, Num a) => StateT a (StateT a m) ()
fibT = get >>= \x -> lift get >>= \y -> put y >> (lift . put $ x + y)

-- Get the nth Fibonacci number
fib :: Num a => Int -> a
fib n = execState (execStateT (replicateM_ n fibT) 0) 1

nvanderw

import System.Environment

sumSquares :: (Integral a) => a -> a
sumSquares n = n*(n+1)*(2*n+1) `div` 6

sumCubes :: (Integral a) => a -> a
sumCubes n = ((n^2 + n) `div` 2)^2

main = do
    args <- getArgs

nvanderw

#!/usr/bin/env bash

# Blacklist commit 1abfdd7
root=$(awk '{print $2}')
objects=$(git rev-list --objects $root | awk '{print $1}')

echo $objects | grep 1abfdd7cb8c67ead50757ea596aa0f01b0ab1389 > /dev/null

if [[ $? -eq 0 ]]
then