Re: unwind-protect?

[Pierre Weis <Pierre.Weis@inria.fr>]

> >From: Pierre Weis <Pierre.Weis@inria.fr>
> 
> >Here, polymorphism, curryfication, and specialization are shining,
> >since you juste have to add one in_* functional application before an
> >actual call to any function f to obtain a specialized evaluation
> >context for f. For instance:
> 
> >let in_tmp f arg = in_directory "/tmp" f arg;;
> 
> Actually, currying gets in the way in this case (as it often does).
> If f takes two arguments, then "in_tmp f x y" will not work as
> expected, but the type-checker will not find the error.
> 
> -- Damien

Right, you have to know that this in_* functions protect the last
application of a function. Hence to apply a curried function you need
parens to partially apply the function, as in_tmp (f x y) z.

Alternatively, you can define your n-ary functions as having tupled
arguments and write in_tmp f (x, y, z) (then the typechecker will find
the ``arity'' errors).

If you had functions with specific arity built-in in the langage, you
would have to define multiple versions of the protect functions, one
for each arity, which is not so appealing...

Pierre Weis

INRIA, Projet Cristal, Pierre.Weis@inria.fr, http://cristal.inria.fr/~weis/