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Matthew Flatt a60f173b46 hash benchmarks and stencil-vector HAMT experiment 
This commit adds an (unused) implementation of immutable hash tables
for Racket CS that trades some run-time performance for an especially
compact representation --- similar to the traditional Racket
implementation of immutable hash tables. It uses a new "stencil
vector" datatype at the Chez Scheme level, which overlays the bitmap
needed for a HAMT node with the Chez-object type tag (and also
provides an update operation that avoids unnecessary memory work).

Compared to the current Racket CS implementation, the stencil-vector
HAMT implementation of an immutable hash table takes only about 1/3
the space on avergae, which translates to a overall 5% savings in
DrRacket's initial heap. It also makes a full Racket build slightly
faster by reducing avergage memory use by 5-10%.

But the run-time performance difference is significant, especially for
the `hash-keys-subset?` operation (at least in microbenchmarks), and
also for addition and iteration. Maybe there's an overall better point
that reduces memory use of the current Patricia trie implementation
without sacrificing as much performance.

Besides the benchmarks and stencil-vector HAMT implementaiton, there
are small changes to the way hash tables cooperate with `equal?`,
which makes it a little easier to plug in different implementations.
2020-01-06 07:07:48 -07:00
.github Add comment to CI step (non-functional) 2019-12-13 08:52:28 +01:00
.gitlab Test all XML collection 2019-11-07 18:18:32 +01:00
pkgs hash benchmarks and stencil-vector HAMT experiment 2020-01-06 07:07:48 -07:00
racket hash benchmarks and stencil-vector HAMT experiment 2020-01-06 07:07:48 -07:00
.gitattributes Don't include git files in archives. 2010-05-12 01:46:05 -04:00
.gitignore Fix typo. 2019-06-21 12:32:37 -05:00
.gitlab-ci.yml Test all XML collection 2019-11-07 18:18:32 +01:00
.mailmap Minor metadata changes. 2019-10-15 08:09:32 -04:00
.travis.yml Try to fix Slack notifications. 2019-10-09 10:24:20 -04:00
build.md racket-build-guide: Don’t decode within exec/commandline 2020-01-02 12:17:07 -06:00
LICENSE Clarify embedded executable issues (#2908) 2019-11-15 21:02:20 -05:00
Makefile makefile: add pre-processing step for distribution creation 2020-01-01 07:13:53 -07:00
README.md Fixed small typo. 2019-12-10 06:09:32 -07:00

README.md

Racket is a general-purpose programming language and an ecosystem for language-oriented programming.

This repository holds the source code for the core of Racket plus some related packages. The rest of the Racket distribution source code is in other repositories, mostly under the Racket GitHub organization.

Quick Start

Pre-built versions of Racket for a variety of operating systems and architectures, as well as convenient source distributions are available at

https://download.racket-lang.org

Racket comes with extensive documentation, including several tutorials. You can read all of this documentation, as well as documentation for third-party packages at

https://docs.racket-lang.org

Building from Source

For information on building Racket from this repository, see the Build Guide.

Contributing

Contribute to Racket by submitting a pull request, reporting an issue, joining the development mailing list, or visiting the IRC or Slack channels.

By making a contribution, you are agreeing that your contribution is licensed under the Apache 2.0 and MIT licenses. Those licenses are available in this repository in the files LICENSE-APACHE.txt and LICENSE-MIT.txt.

License

Racket is free software; see LICENSE for more details.