Throwing errors on mutating immutable bindings

Brendan Eich brendan at
Thu Oct 2 15:51:07 PDT 2014

Isiah Meadows wrote:
> True, and I don't know of a decently fast ES3/5 parser.

What is your use-case? For a parser in JS, is too slow? For C++ hand-coded 
parser, what's your not-decently-fast benchmark basis code?

> ES6 will be even more complicated, and thus, slower than an 
> equivalence ES3/5 one 

I don't think ES6 adds anything that changes asymptotic complexity. 
Recognizing keywords is still O(k), for example (and k is small and 
stays small in ES6 -- number of leading characters to distinguish, 
e.g.). More productions in a grammar does not make parsers for that 
grammar slower, apart from indirect effects in small memory systems.

What do you mean here?


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