Language Size (was Re: [TLUG]: ECMAScript ("Javascript") Version 4 - FALSE ALARM)

Maciej Stachowiak mjs at
Wed Oct 31 03:46:35 PDT 2007

On Oct 30, 2007, at 1:23 PM, Maciej Stachowiak wrote:

> By the way, I think the discussions about language size could benefit
> from some quantitative data. I think the following comparisons would
> be interesting:
> 1) Size of the ES4 grammar relative to the ES3 grammar (say, by count
> of productions).

Excluding the lexical grammar, the E4X syntax rules (which won't be a  
normative requirement) and regular expression syntax, I count:

ECMA-262 3rd Edition: 74 grammar productions
ECMAScript 4th edition draft: 197 grammar productions

That's a more than 2x increase in surface syntax (2.66x to be more  
exact). While not completely unreasonable given all the new features,  
it seems a little high. Before embarking on this exercise I thought  
that 2x would be a reasonable level of core syntax increase. Part of  
this may be simply due to better factoring of the grammar, and due to  
capturing features like auto semicolon insertion, how if is  
disambiguated, noin contexts, etc in more detail.

A lot of the genuinely new stuff just seems to be fallout from the  
type system.

I notice some seemingly duplicate features that will perhaps become  
more clear on closer reading of the spec. For instance I see all three  
of namespace, package and unit productions in the grammar. With my  
limited imagination it's hard to think of how those could be three  
interestingly different features.

> 2) Size of the ES4 standard library by count of classes, methods and
> properties.

I'll try to look at this soon, too. I think 4-5x would be about the  
size that would not raise any red flags for me, given how impoverished  
the ES3 standard library is.

Does anyone else have other ideas for objective metrics of language  


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