return when desugaring to closures

Mark S. Miller erights at
Sat Oct 11 14:55:45 PDT 2008

On Sat, Oct 11, 2008 at 2:42 PM, Brendan Eich <brendan at> wrote:
> We've discussed making use-before-set a strict error, but we've
> avoided it. The initialiser is not mandatory, and we do not wish to
> impose costly analysis on small implementations.

Since "const" use-before-set is an unconditional error (i.e., not
dependent on strictness), implementations already have to pay for a
read-barrier mechanism. Since we'd like to support
type-annotation-constraints on initialized let variables, I think
initialized let variables should have an unconditional read barrier as


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