Global lexical tier

Geoffrey Garen ggaren at apple.com
Tue Sep 1 18:04:07 UTC 2015


> The possible semantics of global lexical declarations was extensively explored by TC39 before we make the final design decisions for ES6.  The scoping of global lexical declarations is something we spent many hours discussing  over a span of several years, including: 

To be fair, some problems in design only become apparent after implementation and use.

For example, in the case of global lexical scope, implementing and testing the details of the current ECMAScript specification led Saam to conclude — and led me to agree — that the behavior was strange, and hard to reason about.

I hope you aren’t saying that ECMAScript decisions should become permanent and irreversible prior to any implementation or adoption effort. In other web standards, implementation and adoption guide specification — to the benefit of the specification.

Geoff


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