Implementor Question

Graydon Hoare graydon at
Tue Oct 30 12:20:02 PDT 2007

Brendan Eich wrote:

> But again, two engines don't cut it, for footprint and memory  
> reasons. And two engines are intentionally unnecessary by the design  
> of ES4.

(Catching up on this thread...)

An additional technical aspect of the language, for newcomers who may 
not have noticed it:

It is also quite intentionally unnecessary in the ES4 design to use 
anything like an AOT-compiler, static typechecker, or fancy 
early-binding toolchain. It's designed to correctly work with 
last-minute checking in a lazy, lightweight, dynamic implementation. 
This was a strong technical requirement made by several committee 
members during 2006 (Opera and Microsoft in particular, iirc), and the 
committee has respected and pursued this goal.

Nearly a dozen alternative semantics were proposed and hashed out by our 
visiting experts in type theory, in order to overcome member 
dissatisfaction with adopting disjoint AS3-like "tilde and bang" modes 
with (from what I understand) somewhat differing semantics.


More information about the Es4-discuss mailing list