[plt-scheme] macro question
On Tue, Jun 10, 2008 at 12:22:56PM -0400, Matthias Felleisen wrote:
>
> On Jun 10, 2008, at 11:40 AM, hendrik at topoi.pooq.com wrote:
> >
> >There are a few type inferences that do not seem to harm the
> >readability of a program. Type information can flow:
> >
> >(a) from the declaration of an identifier to its use
> >
> >(b) from the leaves of a parse tree towards its root (the usual
> >direction of expressino evaluation)
> >
> >(c) from the root of a parse tree towards the leaves (called
> >coercion in
> >Algol 68; a mechanism whereby the context of an expression affects its
> >meaning. Used for determining the types of initializers in C.
> >
>
> None of the above are considered 'type inference.' What you describe
> is the normal mode of type checking.
The fact that it's not confusing may explain why it's normal.
Except for (c). It's often rejected by language designers on principle.
A wrong-headed principle, in my opinion.
-- hendrik