What does FP do well? (was How to get ...)

[Jerzy Karczmarczuk]

Bjorn Lisper:


> ...sometimes the length of a list being returned from a
> function can be a simple function of the function arguments (or the sizes of
> the arguments), think of map for instance. In such cases, a static program
> analysis can sometimes find the length function. If we know thee functions
> for all list-producing functions in a closed program, then the lists could
> be represented by arrays rather than linked structures.
> 
> I know Christoph Herrmann worked on such a program analysis some years
> ago. Also, I think Manuel Hermenegildo has done this for some logic
> language.


Andrew Appel wrote something about "pointer-less" lists as well.

What bothers me quite strongly is the algorithmic side of operations
upon such objects. 

Typical iterations map- (or zip-) style: do something with the head, pass
recursively to the tail, would demand "intelligent" arrays, with the indexing
header detached from the bulk data itself. The "consumed" part could not be
garbage collected. In a lazy language this might possibly produce a considerable
amount of rubbish which otherwise would be destroyed quite fast. The
concatenation of (parts of) such lists might also have very bad behaviour.

Can you calm my anxiety?

Jerzy Karczmarczuk