Monomorphize, was: Re: Proposal for generalized function partition in List-library

[Josef Svenningsson]

John,

On Thu, 17 May 2001, John Meacham wrote:

[..]
> namely that you don't necisarilly know all of the types of polymorphic
> functions when they are in a module that is compiled seperately from the
> rest of the program. the solution used by many C++ compilers is to
> inline all polymorphic code in place (this is why templates are in
> header files). there is no reason this won't work in haskell and give
> back all of the speed benefits of base types everwhere (as it would in
> this example) but has the unfortunate side effect of causing worst case
> exponential code bloat as every function is re-written for every type
> combination it is used with.
>
This is true in ML but not in Haskell. Haskell has polymorphic recursion
which makes it impossible to predict statically at what types a function
will be called. So trying to inline away polymorphism would lead to
infinite unwindings.

Cheers,
	/Josef