[Haskell-cafe] Anonymous, Unique Types, maybe

[Scott Lawrence]

On 12/04/11 02:25, Stephen Tetley wrote:
> Umm, an obvious point is that if you really are using lists as streams
> they should appear infinite to the processing code, so you shouldn't
> encounter operations that fail due to incompatible lengths.

Didn't explain myself quite right, I guess.

The lists are infinite; however, when a function (which doesn't call 
`filter`) produces more than one list, the two lists are related in that 
the nth elements of each list came from the same source. Pairing every 
nth element is meaningfull for two such lists/streams. In contrast, a 
list coming out of `filter` isn't related to the list going in in this 
way, and shouldn't be re-paired with that list (or a direct derivative). 
My goal, again, is to represent that distinction in the type system.

-- 
Scott Lawrence