# Racket v9.3 — Racket v9.3

- Product: Racket (https://whatsnew.fyi/product/racket)
- Vendor: Racket
- Date: 2026-08-13
- Version: v9.3
- Original notes: https://github.com/racket/racket/releases/tag/v9.3
- Permalink: https://whatsnew.fyi/product/racket/releases/v9.3

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

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- **added** — The `raco setup` command can generate markdown documentation using the `--doc-markdown` option
- **changed** — The "#lang" teaching languages (BSL, ISL+, DeinProgram) have reached parity with the ones chosen using the Language dialog and are the recommended choice
- **changed** — DrRacket's background expansion disables errortrace annotations for faster syntax checking
- **added** — The `raco pkg install` command includes new options `--adjacent-deps`, `--destdir`, and `--attach`, and a refined `--skip-installed`
- **added** — The `ffi/unsafe/runtime-lib` library provides a `define-runtime-lib` mechanism similar to `define-runtime-path` for locating libraries relative to a source file
- **changed** — The `prompt-tag/c` contract generator no longer performs checking on `call/cc` when the `#:call/cc` option is not present
- **changed** — The `impersonate-prompt-tag` function takes an additional argument allowing checking and update of results for composable continuations
- **added** — The `error-syntax->srcloc-handler` parameter provides control over the mapping from syntactic forms to source locations for error handling
- **changed** — Uses of `(tcp-listen 0)` will retry when it fails with "address in use"
- **changed** — The `racket/base` module requires fewer internal modules and instantiations
- **added** — The `file/zip` package provides a new mechanism for greatly increased control over zip file generation, allowing in-memory file sources and per-file compression control

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- The `raco setup` command can generate markdown documentation, using
  the `--doc-markdown` option.
- The "#lang" teaching languages (BSL, ..., ISL+; plus DeinProgram)
  have reached parity with the ones chosen using the Language dialog,
  and are the recommended choice.
- DrRacket's background expansion disables errortrace annotations, for
  faster syntax checking.
- The `raco pkg install` command includes new options that provide
  more install-time configuration flexibility: `--adjacent-deps`,
  `--destdir`, and `--attach`, and a refined `--skip-installed`.
- The `ffi/unsafe/runtime-lib` library provides a `define-runtime-lib`
  mechanism similar to `define-runtime-path`, allowing location of
  libraries located relative to a source file.
- The `prompt-tag/c` contract generator no longer performs checking on
  `call/cc` when the `#:call/cc` option is not present.
- The `impersonate-prompt-tag` function takes an additional argument
  that allows checking and update of results for composable
  continuations.
- The `error-syntax->srcloc-handler` parameter provides control over
  the mapping from syntactic forms to source locations for error
  handling.
- Uses of `(tcp-listen 0)` will retry when it fails with "address in
  use".
- The `racket/base` module requires fewer internal modules and
  instantiations.
- The `file/zip` package provides a new mechanism for greatly
  increased control over zip file generation, allowing in-memory file
  sources and per-file compression control.

The following people contributed to this release:

Alex Knauth, Alexander Shopov, Aris Spathis, Bert De Ketelaere, Bob
Burger, Caleb Mazalevskis, Cameron Moy, Geoffrey J. Teale, Gustavo
Massaccesi, Hannes Braun, Jade Sailor, Jason Hemann, Jens Axel
Søgaard, John Clements, Jordan Johnson, Matthew Flatt, Matthias
Felleisen, Mike Sperber, Nathan Dykman, Noah Ma, Philip McGrath,
Robby Findler, Romeo Ahmed, Sam Tobin-Hochstadt, Shu-Hung You,
Stefan Schwarzer, Stephen De Gabrielle, and Wing Hei Chan.

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