Chapter 1. About Alex

Table of Contents

1.1. Release Notes for version 3.0
1.2. Release Notes for version 2.2
1.3. Release Notes for version 2.1.0
1.4. Release Notes for version 2.0
1.4.1. Syntax changes
1.4.2. Changes in the form of an Alex file
1.4.3. Usage changes
1.4.4. Implementation changes
1.5. Reporting bugs in Alex
1.6. License

Alex can always be obtained from its home page. The latest source code lives in the fptools CVS repository; instructions on accessing that repository are here.

1.1. Release Notes for version 3.0

  • 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 asumed 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.