Stable branches are numbered x.y, where y is even. Releases on the stable branch x.y are numbered x.y.z, where z (>= 1) is the patchlevel number. Patchlevels are bug-fix releases only, and never change the programmer interface to any system-supplied code. However, if you install a new patchlevel over an old one you will need to recompile any code that was compiled against the old libraries.

The value of __GLASGOW_HASKELL__ (see Section 4.12.3, “Options affecting the C pre-processor”) for a major release x.y.z is the integer xyy (if y is a single digit, then a leading zero is added, so for example in version 6.8.2 of GHC we would have __GLASGOW_HASKELL__==608).

We may make snapshot releases of the current stable branch available for download, and the latest sources are available from the git repositories.

Stable snapshot releases are named x.y.z.YYYYMMDD. where YYYYMMDD is the date of the sources from which the snapshot was built, and x.y.z+1 is the next release to be made on that branch. For example, 6.8.1.20040225 would be a snapshot of the 6.8 branch during the development of 6.8.2.

The value of __GLASGOW_HASKELL__ for a snapshot release is the integer xyy. You should never write any conditional code which tests for this value, however: since interfaces change on a day-to-day basis, and we don't have finer granularity in the values of __GLASGOW_HASKELL__, you should only conditionally compile using predicates which test whether __GLASGOW_HASKELL__ is equal to, later than, or earlier than a given major release.

We may make snapshot releases of the HEAD available for download, and the latest sources are available from the git repositories.

Unstable snapshot releases are named x.y.YYYYMMDD. where YYYYMMDD is the date of the sources from which the snapshot was built. For example, 6.7.20040225 would be a snapshot of the HEAD before the creation of the 6.8 branch.

The value of __GLASGOW_HASKELL__ for a snapshot release is the integer xyy. You should never write any conditional code which tests for this value, however: since interfaces change on a day-to-day basis, and we don't have finer granularity in the values of __GLASGOW_HASKELL__, you should only conditionally compile using predicates which test whether __GLASGOW_HASKELL__ is equal to, later than, or earlier than a given major release.