[plt-scheme] macro question

From: hendrik at topoi.pooq.com (hendrik at topoi.pooq.com)
Date: Tue Jun 10 12:41:10 EDT 2008

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

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