[Haskell-cafe] ANN: random-access-list-0.1

[Stephan Friedrichs]

Chris Smith wrote:
> Chaddaï Fouché wrote:
>> Given that this structure isn't lazy enough, I really don't see a
>> problem with using Int (any random access list with a size that needs an
>> Integer would blow the memory anyway...).
> 
> Bad way to think about things.  The implications of using Int as the 
> result type of a function extend far beyond just storing the result 
> type.  They also include doing other computations that depend on the 
> result type, and with enough type inference, the broken Int type 
> propogates throughout the program.
> 

I'd like not to be restricted to Int, but what's the proper way to do 
so? Just adding "genericFun = fromInteger . toInteger . fun" functions 
is just as bad as using Ints directly. What I need is something like a 
more general Ix class that is not limited to a fixed interval:

class Ix2 i where
	-- convert starting index and given index to an Int for internal
	-- representation
	toIndex   :: i -> i -> Int

	-- given an internal Int index and a starting index, return the
	-- representing index
	fromIndex :: Int -> i -> i

	-- translate a starting index and a number of elements into a
	-- size
	size      :: i -> Int -> i

This is meant to work with a starting-index and a given index, so that a 
list does not have to start at index 0. Is there something like this? Or 
is it somehow possible to use the existing Ix class to do that?

//Stephan

-- 

Früher hieß es ja: Ich denke, also bin ich.
Heute weiß man: Es geht auch so.

  - Dieter Nuhr