restrictions on let declarations
brendan at mozilla.com
Thu Jan 30 09:24:29 PST 2014
Rick Waldron wrote:
> It is -- special forms that have heads can bind in bodies. We see
> this with formal parameters to functions, also with the defunct
> let blocks and let expressions of ES4. ML has similar forms.
> We made this block scoping, and how! Turns out Dart did the same.
> Each iteration gets a fresh binding. If there's a closure in the
> first part of the for(;;) head that captures the loop variable, it
> gets a "0th iteration" binding.
> Also, there was very positive interest in Waldemar's proposed
> if-scoped let, here:
Nick Krempel proposed that upthread, just for the record.
Yeah, it's good. It comes from C++ but goes back to Algol, IIRC. Another precedent for block-scoped bindings that are declared in heads.
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