[plt-scheme] typed scheme vs. PLAI types

From: Noel Welsh (noelwelsh at gmail.com)
Date: Tue Feb 16 05:38:01 EST 2010

On Tue, Feb 16, 2010 at 10:09 AM, keydana at gmx.de <keydana at gmx.de> wrote:
> Still, I don't understand in which cases I have to annotate an expression?

Whenever the type inference algorithm can't infer it :)

Honestly, I don't know. It seems that functions must be annotated but
other values do not.require annotation. I annotate all module level
bindings and internal function definitions.

> Also, when I try annotating (although in the following case it's not necessary it seems, as suppliers_1-3 is constructed as a Relation) like this:
> (ann suppliers_1_3 Relation)
> I get the error
> . Type Checker: Unbound type name Relation in: Relation
> which I don't understand.

Dunno. I'd have to look over your code again, but I've deleted it from
my inbox :( Maybe Sam can help.


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