On Jan 5, 2012, at 5:32 PM, Sam Tobin-Hochstadt wrote: > On Thu, Jan 5, 2012 at 11:56 PM, John Clements > <cleme...@brinckerhoff.org> wrote: >> I wrote a piece of code like this without thinking: >> >> #lang typed/racket >> >> (: f (All (T) (Number -> T -> T))) >> (define ((f x) y) >> (ann y T)) >> >> ... and then, after a second, was sort of flabbergasted that it worked. >> What's the scope of the type variable T? Apparently I can use it anywhere in >> the definition of the identifier that it names? That seems really fragile. >> Am I misunderstanding this? > > You're correct about the scope, and the fact that you wrote it without > thinking, and it just did the right thing, is precisely what I was > going for. What's fragile here?
Okay, yes, it makes sense. The scope is not defined by a pair of parentheses, but I guess I can get past that; after all, our internal defines are headed in that direction, too. John
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