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cisco
ChezScheme
Scheme2016–2025
cisco / ChezScheme

ChezScheme

Chez Scheme

26Distinct people
34Mentions
0Explicit recommenders
7.4KGitHub stars
REPOSITORY AT A GLANCE

What to know before exploring

What it is

Chez Scheme

GitHub

Where it is used

No documented product use was verified in the last source check.

What people are saying

No recommendation phrase was found in the indexed comments.

No classified warning is attached to this page. Read the discussions before treating silence as approval.

Also in these discussions

No other repository is repeatedly linked in the same discussions.

This week on Hacker News

Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 3:03:16 PM UTC.

No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.

Mentions over time

HN mentions by year34 dated mentions

Observed mentions: 2016-04-26 15:11:27 UTC to 2025-11-10 17:25:51 UTC.

02462016-01-01 00:00:00 UTC to 2017-01-01 00:00:00 UTC (exclusive): 4 mentions; 1 submissions, 3 comments20162017-01-01 00:00:00 UTC to 2018-01-01 00:00:00 UTC (exclusive): 7 mentions; 1 submissions, 6 comments2018-01-01 00:00:00 UTC to 2019-01-01 00:00:00 UTC (exclusive): 3 mentions; 0 submissions, 3 comments2019-01-01 00:00:00 UTC to 2020-01-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 comments2020-01-01 00:00:00 UTC to 2021-01-01 00:00:00 UTC (exclusive): 2 mentions; 1 submissions, 1 comments20202021-01-01 00:00:00 UTC to 2022-01-01 00:00:00 UTC (exclusive): 2 mentions; 0 submissions, 2 comments2022-01-01 00:00:00 UTC to 2023-01-01 00:00:00 UTC (exclusive): 2 mentions; 1 submissions, 1 comments2023-01-01 00:00:00 UTC to 2024-01-01 00:00:00 UTC (exclusive): 3 mentions; 0 submissions, 3 comments2024-01-01 00:00:00 UTC to 2025-01-01 00:00:00 UTC (exclusive): 5 mentions; 3 submissions, 2 comments2025-01-01 00:00:00 UTC to 2026-01-01 00:00:00 UTC (exclusive): 5 mentions; 2 submissions, 3 comments2025

Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.

View mention counts and date ranges
UTC ranges include their start and exclude their end. Select a period to filter the source evidence.
PeriodStart (UTC)End (exclusive, UTC)MentionsSubmissionsComments
20162016-01-01 00:00:00 UTC2017-01-01 00:00:00 UTC413
20172017-01-01 00:00:00 UTC2018-01-01 00:00:00 UTC716
20182018-01-01 00:00:00 UTC2019-01-01 00:00:00 UTC303
20192019-01-01 00:00:00 UTC2020-01-01 00:00:00 UTC101
20202020-01-01 00:00:00 UTC2021-01-01 00:00:00 UTC211
20212021-01-01 00:00:00 UTC2022-01-01 00:00:00 UTC202
20222022-01-01 00:00:00 UTC2023-01-01 00:00:00 UTC211
20232023-01-01 00:00:00 UTC2024-01-01 00:00:00 UTC303
20242024-01-01 00:00:00 UTC2025-01-01 00:00:00 UTC532
20252025-01-01 00:00:00 UTC2026-01-01 00:00:00 UTC523

From the project README

An excerpt from the repository, fetched Nov 13, 2026.

Read the project’s introduction
Tip: Clone this repo with git clone --filter=blob:none to avoid eagerly downloading large boot files for older versions. Chez Scheme is both a programming language and an implementation of that language, with supporting tools and documentation. Supported platforms (bytecode interpreter may work for others): Windows: x86, x86_64, AArch64 Mac OS: x86, x86_64, AArch64, PowerPC32 Linux: x86, x86_64, ARMv6, AArch64, RV64G, LoongArch64, PowerPC32 FreeBSD: x86, x86_64, ARMv6, AArch64, PowerPC32 OpenBSD: x86, x86_64, ARMv6, AArch64, PowerPC32 NetBSD: x86, x86_64, ARMv6, AArch64, PowerPC32 Solaris: x86, x86_64 GNU/Hurd: x86, x86_64 Haiku: x86_64 Android: ARMv7, AArch64 iOS: AArch64 WebAssembly via Emscripten (bytecode interpreter only) As a superset of the language described in the Revised6 Report on the Algorithmic Language Scheme (R6RS), Chez Scheme supports all standard features of Scheme, including first-class procedures, proper treatment of tail calls, continuations, user-defined records, libraries, exceptions, and hygienic macro expansion. Chez Scheme also includes extensive support for interfacing with C and other languages, support for multiple threads possibly running on multiple cores, non-blocking I/O, and many other features. The Chez Scheme implementation consists of a compiler, run-time system, and programming environment. Although an interpreter is available, all code is compiled by default. Source code is compiled on-the-fly when loaded from a source file or entered via the shell. A source file can also be precompiled into a stored binary form and automatically recompiled when its dependencies change. Whether compiling on the fly or precompiling, the compiler produces optimized machine code, with some optimization across separately compiled library boundaries. The compiler can also be directed to perform whole-program compilation, which does full cross-library optimization and also reduces a program and the libraries upon which it depends to a single binary. The run-time system interfaces with the operating system and supports, among other things, binary and textual (Unicode) I/O, automatic storage management (dynamic memory allocation and generational garbage collection), library management, and exception handling. By default, the compiler is included in the run-time system, allowing programs to be generated and compiled at run time, and storage for dynamically compiled code, just like any other dynamically allocated storage, is automatically reclaimed by the garbage collector. The programming environment includes a source-level debugger, a mechanism for producing HTML displays of profile counts and program "hot spots" when profiling is enabled during compilation, tools for inspecting memory usage, and an interactive shell interface (the expression editor, or "expeditor" for short) that supports multi-line expression editing. The R6RS core of the Chez Scheme language is described in The Scheme Programming Language, which also includes an introduction to Scheme and a set of example programs. Chez Scheme's additional language, run-time system, and programming environment features are described in the Chez Scheme User's Guide. The latter includes a shared index and a shared summary of forms, with links where appropriate to the former, so it is often the best starting point. Get started with Chez Scheme by Building Chez Scheme. For more information about the implementation and a guide to modifying Chez Scheme, see implementation notes. For more information on Chez Scheme, see the Chez Scheme Project Page.
Read the full README on GitHub

What Hacker News says

34 sources
Kent Dybvig also wrote Chez Scheme [1] which on most benchmarks is far-and-away the fastest [2] Scheme implementation. Racket recently got rewritten to be based off of Chez [3] and I have it from the maintainer of Racket himself that it’s paid off well: better performance and a smaller, more maintainable codebase. 1: https://github.com/cisco/ChezScheme (also, pronounced “Shay Scheme”) 2: https://ecraven.github.io/r7rs-benchmarks/ 3: https://m.youtube.com/watch?v=s3Q3M2wZ7rI&pp=0gcJCRsBo7VqN5t...
In Show HN: Kent Dybvig's Scheme Machine in 400 Lines of C (Heap-Memory Model)
Thanks! [Sorry for the delay.] --- FYI: For more context, I'm trying to send a PR to Chez Scheme (and indirectly to Racket) https://github.com/cisco/ChezScheme/pull/959 to reduce expressions like (+ 1.0 (length L)) ; ==> (+ 1.0 (fixnum->flonum (length L))) where the "fixnums" are small integers and "flonums" are double. It's fine, unless you have the case (+ -0.0 (length L)) ; =wrong=> (+ -0.0 (fixnum->flonum (length L))) because if the length is 0, it get's transformed into 0.0 instead of -0.0 There are a few corner cases, in particular because it's possible to have (+ 1.0 x (length L)) and I really want to avoid the runtime check of (length L) == 0 if possible. So I took a look, asked there, and now your opinion confirms what I got so far. My C is not very good, so it's nice to have a example of how the rounding directio
Read the rest
ns are used. Luckily Chez Scheme only uses the default rounding and it's probably correct to cut a few corners. I'll take a looks for a few days in case there is some surprise.
In Ask HN: How is it possible to get -0.0 in a sum?
> Contrived example being that Lisp "knows" about Structs and CLOS, whereas while you can add Structs (records) to Scheme, at a Scheme level you can only reduce them to the given Scheme primitives (vectors or lists), when the compiler finally sees the result, all it will see is a vector or list, with no knowledge of it actually being a struct (and thus can't potentially optimized for it). I don't know every single implementation of Scheme, but at least the Chez Scheme compiler has a lot of special code for records. The compiler sees them as records, tries to inline as many getters and setters as possible, and has low level support for the tree of subrecords and I may be missing a few more tricks. You can go to https://github.com/cisco/ChezScheme/blob/main/s/cp0.ss and Ctr+F record . For example https://github.com/cisco/ChezScheme/blob/ma
Read the rest
in/s/cp0.ss#L3816... The old implementation of Racket also had some tricks, but now the structs are transformed to Chez Scheme records.
In CIEL Is an Extended Lisp

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