[cap-talk] David Wagner's Google techtalk is now up!

Jonathan S. Shapiro shap at eros-os.com
Thu Dec 13 13:57:03 EST 2007


On Thu, 2007-12-13 at 13:38 -0500, Jonathan S. Shapiro wrote:
> There are
> real restrictions that a safe static type system imposes. One, which
> MarkM can explain better than I, is that static types and first-class
> messages are not really compatible (more precisely: first class reply
> messages) within the current state of the art of type theory.

A bit of follow up on this. Recently, Scott Smith, Swaroop, and I were
discussing the typed I/O problem, and the apparent need for checked
dynamic upcast in any sensible static language. We identified a set of
criteria under which the result of a checked upcast may alias the
untyped (really: vector of bytes) state originally delivered by the I/O
system.

Granting that this is not a fully static check, my question to MarkM is:
would the first-class reply message issue be sufficiently resolved (in a
pragmatic sense) by treating the low-level reply as a vector of
characters and using checked upcast to get out the appropriate reply
type?


shap



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