[Haskell-cafe] Does somebody know about these functions?

[Holger Siegel]

Am 28.02.2012 um 18:06 schrieb Johan Holmquist:

> Two functions that I see useful are described here and I would like to
> know if they are defined in some more or less standard Haskell
> library. Hoogle (http://www.haskell.org/hoogle) did not reveal
> anything about that.
> 
> 
> Function 'inter' applies given function to each succeeding pair of
> elements of a list.
> 
> inter :: (a -> a -> b) -> [a] -> [b]
> inter f [] = []
> inter f l  = map (uncurry f) $ zip l (tail l)

This is the same as

  inter :: (a -> a -> b) -> [a] -> [b]
  inter f l = zipWith f l (tail l)

and you can use it to define the good old Fibonacci sequence:

  fibs = 0 : 1 : inter (+) fibs