alex

Alex is a tool for generating lexical analysers in Haskell http://www.haskell.org/alex/

Version on this page:3.1.7
LTS Haskell 15.15:3.2.5
Stackage Nightly 2020-06-06:3.2.5
Latest on Hackage:3.2.5

See all snapshots alex appears in

BSD-3-Clause licensed by Chris Dornan and Simon Marlow
Maintained by Simon Marlow

Module documentation for 3.1.7

This version can be pinned in stack with:[email protected]:bd647b9fac1b1cae339a158925a237e671d91ec1d3d898d813c617f12fc6ee5a,2872

There are no documented modules for this package.

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++.

Changes

Changes in 3.1.7:

  • Add support for %encoding directive (allows to control --latin1 from inside Alex scripts)
  • Make code forward-compatible with in-progress proposals
  • Suppress more warnings

Changes in 3.1.6:

  • sdist for 3.1.5 was mis-generated, causing it to ask for Happy when building.

Changes in 3.1.5:

  • Generate less warning-laden code, and suppress other warnings.
  • Bug fixes.

Changes in 3.1.4:

  • Add Applicative/Functor instances for GHC 7.10

Changes in 3.1.3:

  • Fix for clang (XCode 5)

Changes in 3.1.2:

  • Add missing file to extra-source-files

Changes in 3.1.1:

  • Bug fixes (#24, #30, #31, #32)

Changes in 3.1.0:

  • necessary changes to work with GHC 7.8.1

Changes in 3.0 (since 2.3.5)

  • Unicode support (contributed mostly by Jean-Philippe Bernardy, with help from Alan Zimmerman).

    • An Alex lexer now takes a UTF-8 encoded byte sequence as input (see Section 5.1, “Unicode and UTF-8”. If you are using the “basic” wrapper or one of the other wrappers that takes a Haskell String as input, the string is automatically encoded into UTF-8 by Alex. If your input is a ByteString, you are responsible for ensuring that the input is UTF-8 encoded. The old 8-bit behaviour is still available via the –latin1 option.

    • Alex source files are assumed to be in UTF-8, like Haskell source files. The lexer specification can use Unicode characters and ranges.

    • alexGetChar is renamed to alexGetByte in the generated code.

    • There is a new option, --latin1, that restores the old behaviour.

  • Alex now does DFA minimization, which helps to reduce the size of the generated tables, especially for lexers that use Unicode.