hellertime

intervals :: (Eq a, Enum a) => [a] -> [(a, Maybe a)]
intervals []     = []
intervals (x:[]) = [(x, Nothing)]
intervals (x:xs) = (x, lastSuccessor x x xs) : intervals (dropSuccessors x xs)
  where
    lastSuccessor :: (Eq a, Enum a) => a -> a -> [a] -> Maybe a
    lastSuccessor l x []
        | l == x                  = Nothing
        | otherwise               = Just x
    lastSuccessor l x (y:ys)

hellertime

import sys
# requires Python 2.5
assert sys.version_info[1] >= 5, "Requires Python Coroutines. See PEP 0342"

def pushbackiter(iterator):
    """converts 'iterator' into a coroutine, with limited pushback

    >>> it = pushbackiter([1,2,3,4,5])
    >>> it.next()
    1

hellertime

> import Control.Exception ( handle, IOException )

here is a specialize handle which deals with IOExceptions

> handleIO :: (IOException -> IO a) -> IO a -> IO a
> handleIO = handle

Without this added signature you will get type-check errors like this:

    Ambiguous type variable `e' in the constraint:

hellertime

> import Distribution.Simple

This is an example Setup.hs for a haskell program making use of HaskellDB.

> import System.Directory ( removeFile, removeDirectoryRecursive )

HaskellDB needs to have the structure of all database tables laid out as data. 

> import Database.HaskellDB
> import Database.HaskellDB.DBSpec