alex: Alex is a tool for generating lexical analysers in Haskell
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Alex is a tool for generating lexical analysers in Haskell. It takes a description of tokens based on regular expressions and generates a Haskell module containing code for scanning text efficiently. It is similar to the tool lex or flex for C/C++.
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Properties
| Versions | 2.1.0, 2.2, 2.3, 2.3.1, 2.3.2, 2.3.3, 2.3.4, 2.3.5, 3.0, 3.0.1, 3.0.2, 3.0.3, 3.0.4, 3.0.5, 3.1.0, 3.1.1, 3.1.2, 3.1.3, 3.1.4, 3.1.5, 3.1.6, 3.1.7, 3.2.0, 3.2.1, 3.2.2, 3.2.3, 3.2.4, 3.2.5, 3.2.6, 3.2.6, 3.2.7, 3.2.7.1, 3.2.7.2, 3.2.7.3, 3.2.7.4, 3.3.0.0, 3.4.0.0, 3.4.0.1, 3.5.0.0, 3.5.1.0, 3.5.2.0 |
|---|---|
| Change log | CHANGELOG.md |
| Dependencies | array, base (>=1.0 && <5), containers, directory [details] |
| License | BSD-3-Clause |
| Copyright | (c) Chis Dornan, Simon Marlow |
| Author | Chris Dornan and Simon Marlow |
| Maintainer | Simon Marlow <marlowsd@gmail.com> |
| Category | Development |
| Home page | http://www.haskell.org/alex/ |
| Bug tracker | https://github.com/simonmar/alex/issues |
| Source repo | head: git clone https://github.com/simonmar/alex.git |
| Uploaded | by JohnEricson at 2020-12-15T05:15:07Z |
Flags
Automatic Flags
| Name | Description | Default |
|---|---|---|
| small_base | Choose the new smaller, split-up base package. | Enabled |
Use -f <flag> to enable a flag, or -f -<flag> to disable that flag. More info
Downloads
- alex-3.2.6.tar.gz [browse] (Cabal source package)
- Package description (as included in the package)
Maintainer's Corner
Package maintainers
For package maintainers and hackage trustees
Readme for alex-3.2.6
[back to package description]Alex: A Lexical Analyser Generator
Alex is a Lex-like tool for generating Haskell scanners. For complete documentation, see the doc directory.
Alex version 2.0 has changed fairly considerably since version 1.x, and the syntax is almost completely different. For a detailed list of changes, see the release notes in the documentation.
Alex is now covered by a BSD-Style licence; see the licence file in the 'doc' directory for details.
The sources are in the 'src' directory and the documentation in the 'doc' directory; various examples are in the 'examples' subdirectory.
The source code in the 'src' and 'examples' directories is intended for a Haskell 98 compiler with hierarchical modules. It should work with GHC >= 5.04.
Build Instructions
If you just want to use Alex, you can download or install (via
cabal install alex) an
Alex release from Hackage; also note that
distributions such as the
Haskell Platform and other package
manager-based distributions provide packages for Alex. Moreover,
recent versions of cabal will automatically install the required
version of alex based on
build-tools/build-tool-depends declarations.
Read on if you want to build Alex directly from Git.
Alex is built using GHC & Cabal; so first install
GHC and
cabal-install-2.0 (or later).
Since Alex itself is implemented in terms of an Alex scanner, bootstrapping Alex is a bit tricky:
You need to have the build-tools alex and happy manually
installed; either via your system package manager distribution, the
Haskell Platform, or e.g. via (run this outside the Git repository!):
$ cabal install alex happy
which installs them into ${HOME}/.cabal/bin by default (make sure
they're in your $PATH for the next steps!).
Variant A
First you need to generate the pre-processed templates via
$ cabal new-run gen-alex-sdist
(otherwise cabal install will complain about
"data/AlexTemplate: copyFile: does not exist (No such file or directory)")
And then you can install alex simply by invoking
$ cabal install
from inside the Git folder.
Variant B
Alternatively, you can use the Makefile which automates the steps of
producing a self-contained pre-bootstrapped source distribution with
pre-generated lexer/scanners (and which also performs the cabal new-run gen-alex-sdist pre-preprocessing step):
$ make sdist
$ cabal install dist/alex-*.tar.gz
For convenience, there's also a make sdist-test target which builds the
source source tarball and runs the test-suite from within the source dist.
Contributing & Reporting Issues
Please report any bugs or comments at https://github.com/simonmar/alex/issues
Share and enjoy,
Chris Dornan: cdornan@arm.com
Isaac Jones: ijones@syntaxpolice.org
Simon Marlow: simonmar@microsoft.com