README.md
1# Alex: A Lexical Analyser Generator
2
3[](http://travis-ci.org/simonmar/alex)
4
5Alex is a Lex-like tool for generating Haskell scanners. For complete
6documentation, see the doc directory.
7
8- <https://www.haskell.org/alex/>
9
10- <https://hackage.haskell.org/package/alex>
11
12Alex version 2.0 has changed fairly considerably since version 1.x,
13and the syntax is almost completely different. For a detailed list of
14changes, see the release notes in the documentation.
15
16Alex is now covered by a BSD-Style licence; see the licence file in
17the 'doc' directory for details.
18
19The sources are in the 'src' directory and the documentation in the 'doc'
20directory; various examples are in the 'examples' subdirectory.
21
22The source code in the 'src' and 'examples' directories is intended
23for a Haskell 98 compiler with hierarchical modules. It should work
24with GHC >= 5.04.
25
26## Build Instructions
27
28If you just want to *use* Alex, you can download or install (via
29`cabal install alex`) an
30[Alex release from Hackage](https://hackage.haskell.org/package/alex); also note that
31distributions such as the
32[Haskell Platform](https://www.haskell.org/platform/) and other package
33manager-based distributions provide packages for Alex. Moreover,
34recent versions of `cabal` will automatically install the required
35version of `alex` based on
36[`build-tools`/`build-tool-depends` declarations](http://cabal.readthedocs.io/en/latest/developing-packages.html#pkg-field-build-tool-depends).
37
38Read on if you want to build Alex directly from Git.
39
40Alex is built using GHC & Cabal; so first install
41[GHC](https://www.haskell.org/ghc) and
42[`cabal-install-2.0`](https://www.haskell.org/cabal) (or later).
43
44Since Alex itself is implemented in terms of an Alex scanner,
45bootstrapping Alex is a bit tricky:
46
47You need to have the build-tools `alex` and `happy` manually
48installed; either via your system package manager distribution, the
49Haskell Platform, or e.g. via (run this outside the Git repository!):
50
51 $ cabal install alex happy
52
53which installs them into `${HOME}/.cabal/bin` by default (make sure
54they're in your `$PATH` for the next steps!).
55
56### Variant A
57
58First you need to generate the pre-processed templates via
59
60 $ cabal new-run gen-alex-sdist
61
62(otherwise `cabal install` will complain about
63"`data/AlexTemplate: copyFile: does not exist (No such file or directory)`")
64
65And then you can install `alex` simply by invoking
66
67 $ cabal install
68
69from inside the Git folder.
70
71### Variant B
72
73Alternatively, you can use the `Makefile` which automates the steps of
74producing a self-contained pre-bootstrapped source distribution with
75pre-generated lexer/scanners (and which also performs the `cabal
76new-run gen-alex-sdist` pre-preprocessing step):
77
78 $ make sdist
79 $ cabal install dist/alex-*.tar.gz
80
81For convenience, there's also a `make sdist-test` target which builds the
82source source tarball and runs the test-suite from within the source dist.
83
84## Contributing & Reporting Issues
85
86Please report any bugs or comments at https://github.com/simonmar/alex/issues
87
88Share and enjoy,
89
90Chris Dornan: cdornan@arm.com
91
92Isaac Jones: ijones@syntaxpolice.org
93
94Simon Marlow: simonmar@microsoft.com
95
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