IDE support?

John J Barton johnjbarton at
Mon Sep 12 17:05:28 PDT 2011

> From: "François REMY" <fremycompany_pub at>
> To: <es-discuss at>
> Date: Mon, 12 Sep 2011 22:31:17 +0200
> Subject: Re: IDE support?
> Types are not only "desirable" to borrow concepts from current IDEs. We know from DotNET that a language running in a VM can be pretty fast, close to a native language. But it has to be simple for the computer. JavaScript is simple for the developer, but sometimes its flexibility makes it impossible to "optimize" code properly. And it makes JavaScript slower.
> Or, to be exact, it doesn't allow to make 95% of our code faster because it would break the other 5%. The more a compiler understand what you're doing, the more it will be confident that optimizing is safe. Types may be part of the data a compiler may use. It doesn't need to be the only one, but it can be a very important one.

Ah, but let's be exact then: what proportion of most Web applications
will benefit from type-based performance improvements?

The reason I ask is that the diagrams that Wes posted show two things.
One is obvious: the dramatic improvement in JS. Yay! Congrats to all

The other is less obvious: further improvements in JS performance are
less and less important.  Not "unimportant" and not "insignficant".
Just less important because the total performance depends on many
factors of which JS -- for most pages most of the time -- may no
longer be the critical factor.  And even when JS is important,
type-based improvements will only be a small factor really. In the big
picture, such a fundamental change may not be very valuable.

Of course I am guessing, and having real performance analysis numbers
would be excellent information.


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