Re: RFC: general sequences

On Tue, 24 May 2005, Duncan Coutts wrote:

On Tue, 2005-05-24 at 11:23 +0100, Malcolm Wallace wrote:

...

Ross Paterson writes:

...

Also, there was debate at the time of the Haskell'98 committee about whether the list operations with an Int argument would be better taking an Integer. I believe the consensus was positive towards unbounded Integer, but it was important for the standard to be backwards compatible, so Int remained. However, with a new library, you have the opportunity to get it right from the start.

There is also the argument that an Int is always big enough to be used as an index into a data structure that can fit in memory. This also applies to 64 bit machines because the Int just gets bigger. And so the argument goes, if Int is sufficient then there is the performance advantage of simple machine integers.

A list can be infinite, the garbage collector can throw away nodes with small indices. So it is possible to access nodes above INT_MAX. E.g. x!!(1e10) will generate 1e10 nodes but not all of them are hold in memory.