7. Package Description Format Specification History

Package descriptions need to specify the version of the specification they need to be interpreted in via the cabal-version declaration. The following list describes changes that occurred in each version of the cabal specification relative to the respective preceding published version.

Note

The sequence of specification version numbers is not contiguous because it’s synchronised with the version of the Cabal library. As a consequence, only even versions are considered proper published versions of the specification as odd versions of the Cabal library denote unreleased development branches which have no stability guarantee.

7.1. cabal-version: 3.0

  • Added the extra-dynamic-library-flavours field to specify non-trivial variants of dynamic flavours. It is extra-library-flavours but for shared libraries. Mainly useful for GHC’s RTS library.

  • Free text fields (e.g. description) preserve empty lines and indentation. In other words, you don’t need to add dots for blank lines.

  • License fields use identifiers from SPDX License List version 3.6 2019-07-10

  • Remove deprecated hs-source-dir, extensions and build-tools fields.

  • Common stanzas are now allowed also in the beginnning of conditional sections. In other words, the following is valid

    library
    import deps

    if flag(foo)
        import foo-deps

  • Allow redundant leading or trailing commas in package fields with optional commas, such as exposed-modules

  • Require fields with optional commas to consistently omit or place commas between elements.

  • Changed the behavior of extra-bundled-libraries field. The naming convention of dynamic library files (e.g. generated by a custom build script) has changed. For library names prefixed with “C”, the dynamic library file name(s) must be of the form lib<library-name>.<dyn-library-extension>* instead of the old libC<library-name>-ghc<ghc-flavour><ghc-version>.<dyn-library-extension>

  • New set-notation syntax for == and ^>= operators, see build-depends field documentation for examples.

  • Allow more whitespace in mixins field

  • Wildcards are disallowed in pkgconfig-depends, Yet the pkgconfig format is relaxed to accept e.g. versions like 1.1.0h.

  • New autogen-includes for specifying install-includes which are autogenerated (e.g. by a configure script).

  • New asm-sources and asm-options fields added for suppporting bundled foreign routines implemented in assembler.

  • New cmm-sources and cmm-options fields added for suppporting bundled foreign primops implemented in C–.

7.2. cabal-version: 2.4

  • Wildcard matching has been expanded. All previous wildcard expressions are still valid; some will match strictly more files than before. Specifically:
    • Double-star (**) wildcards are now accepted for recursive matching immediately before the final slash; they must be followed by a filename wildcard (e.g., foo/**/*.html is valid; foo/**/bar/*.html and foo/**/**/*.html, foo/**/bar.html are all invalid). As ** was an error in globs before, this does not affect any existing .cabal files that previously worked.
    • Wildcards now match when the pattern’s extensions form a suffix of the candidate file’s extension, rather than requiring strict equality (e.g., previously *.html did not match foo.en.html, but now it does).
  • License fields use identifiers from SPDX License List version 3.2 2018-07-10

7.3. cabal-version: 2.2

  • New common stanzas and import pseudo-field added.
  • New library:virtual-modules field added.
  • New cxx-sources and cxx-options fields added for suppporting bundled foreign routines implemented in C++.
  • New extra-bundled-libraries field for specifying additional custom library objects to be installed.
  • Extended if control structure with support for elif keyword.
  • Changed default rules of build-type field to infer “build-type:” for “Simple”/”Custom” automatically.
  • license field syntax changed to require SPDX expression syntax (using SPDX license list version 3.0 2017-12-28).
  • Allow redundant leading or trailing commas in package fields (which require commas) such as build-depends.

7.4. cabal-version: 2.0

7.5. cabal-version: 1.24

  • New custom-setup stanza and custom-setup:setup-depends field added for specifying dependencies of custom Setup.hs scripts.
  • CPP Macros VERSION_$pkgname and MIN_VERSION_$pkgname are now also generated for the current package.
  • New CPP Macros CURRENT_COMPONENT_ID and CURRENT_PACKAGE_KEY.
  • New extra-framework-dirs field added for specifying extra locations to find OS X frameworks.

7.6. cabal-version: 1.22

7.7. cabal-version: 1.20

  • Add support for new license-files field for declaring multiple license documents.
  • New CPP Macro MIN_TOOL_VERSION_$buildtool.
  • New license types BSD2 and MPL-2.0 added.

7.8. cabal-version: 1.18

  • Add support for new extra-doc-files field for specifying extra file assets referenced by the Haddock documentation.
  • New license type AGPL and AGPL-3 added.
  • Add support for specifying a C/C++/obj-C source file in executable:main-is field.
  • Add getSysconfDir operation to Paths_ API.

7.9. cabal-version: 1.16

Todo

this needs to be researched; there were only few changes between 1.12 and 1.18;

7.10. cabal-version: 1.12

  • Change syntax of cabal-version to support the new recommended cabal-version: x.y style