One way is to write an else branch that returns a value that is not the 
expected result type. Exhaustion of the elements of a union by previous 
branches would cause the typechecker to determine the reachability of that 
branch impossible and not report an error.
-Ian
----- Original Message -----
From: Eric Tanter <etan...@dcc.uchile.cl>
To: Racket Users <users@racket-lang.org>
Sent: Thu, 20 Oct 2011 10:48:22 -0400 (EDT)
Subject: [racket] [typed racket] type case

Hi again,

Is there a mechanism to do an exhaustive type case?

I know I can use (cond [(type-pred? v) ...]
                       [...])

but of course I have no guarantee that I am exhaustive (and of course, doing 
pattern matching to destruct the value would be even nicer). 

Basically, I guess I'm after the typed version of PLAI's type-case.

Thanks,

-- Éric



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