[Haskell-cafe] Fast JSON validation - reducing allocations

Bardur Arantsson spam at scientician.net
Thu May 11 17:11:04 UTC 2017

On 2017-05-11 18:59, David Turner wrote:
> Interesting, thanks for the link. However we're trying to do _even less_
> than that - this is just the "scan the document to produce the
> Elias-Fano encoding" step, except without needing to keep a hold of it
> for later. It's not quite as trivial as that paper makes out as (a) it
> doesn't mention the possibility that the documents might not be
> well-formed, and (b) it doesn't really talk about dealing with the
> special delimiting characters within string literals, for which you need
> to drag along a bunch of state while you're scanning.

My thinking was actually that it could be used reduce the allocations
since everything (AFAIR, it's been a while) would basically just be
linear datastructures and indexes.

> This'd be pretty trivial to do in a C-like language now we've got the
> DFA tables built, and I may resort to that at some point if we can't
> work out how to avoid the allocations in Haskell-land, but I'd quite
> like to be able to solve problems of this form without unnecessarily
> resorting to C.

We'll there's always




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