[Haskell-cafe] Re: A bit of a shock - Memoizing functions

[David Menendez]

2009/3/27 Kirk Martinez <kirk.martinez at gmail.com>:
> It seems there is a very close correspondence between data structures and
> functions in Haskell.  Your powersOfTwo function, since it gets memoized
> automatically (is this the case for all functions of zero arguments?), seems
> exactly like a data structure.

That's because it is. It's an array whose elements are computed on demand.

>  This harks back to my Scheme days when we
> learned about the close relationship between code and data.
>
> I wonder: does the converse exist?  Haskell data constructors which are
> really functions?  How and for what might one use those?

Sure. You can use Church encoding to represent any Haskell data type
as a function.

-- 
Dave Menendez <dave at zednenem.com>
<http://www.eyrie.org/~zednenem/>