Cabal- A framework for packaging Haskell software

CopyrightIsaac Jones 2003-2004
Safe HaskellNone




This should be a much more sophisticated abstraction than it is. Currently it's just a bit of data about the compiler, like it's flavour and name and version. The reason it's just data is because currently it has to be in Read and Show so it can be saved along with the LocalBuildInfo. The only interesting bit of info it contains is a mapping between language extensions and compiler command line flags. This module also defines a PackageDB type which is used to refer to package databases. Most compilers only know about a single global package collection but GHC has a global and per-user one and it lets you create arbitrary other package databases. We do not yet fully support this latter feature.


Haskell implementations

data Compiler




compilerId :: CompilerId

Compiler flavour and version.

compilerAbiTag :: AbiTag

Tag for distinguishing incompatible ABI's on the same architecture/os.

compilerCompat :: [CompilerId]

Other implementations that this compiler claims to be compatible with.

compilerLanguages :: [(Language, Flag)]

Supported language standards.

compilerExtensions :: [(Extension, Flag)]

Supported extensions.

compilerProperties :: Map String String

A key-value map for properties not covered by the above fields.


Eq Compiler 
Read Compiler 
Show Compiler 
Generic Compiler 
Binary Compiler 
type Rep Compiler 

Support for package databases

data PackageDB

Some compilers have a notion of a database of available packages. For some there is just one global db of packages, other compilers support a per-user or an arbitrary db specified at some location in the file system. This can be used to build isloated environments of packages, for example to build a collection of related packages without installing them globally.


Eq PackageDB 
Ord PackageDB 
Read PackageDB 
Show PackageDB 
Generic PackageDB 
Binary PackageDB 
type Rep PackageDB 

type PackageDBStack = [PackageDB]

We typically get packages from several databases, and stack them together. This type lets us be explicit about that stacking. For example typical stacks include:

[GlobalPackageDB, UserPackageDB]
[GlobalPackageDB, SpecificPackageDB "package.conf.inplace"]

Note that the GlobalPackageDB is invariably at the bottom since it contains the rts, base and other special compiler-specific packages.

We are not restricted to using just the above combinations. In particular we can use several custom package dbs and the user package db together.

When it comes to writing, the top most (last) package is used.

registrationPackageDB :: PackageDBStack -> PackageDB

Return the package that we should register into. This is the package db at the top of the stack.

absolutePackageDBPaths :: PackageDBStack -> IO PackageDBStack

Make package paths absolute

Support for optimisation levels

data OptimisationLevel

Some compilers support optimising. Some have different levels. For compilers that do not the level is just capped to the level they do support.

Support for debug info levels

data DebugInfoLevel

Some compilers support emitting debug info. Some have different levels. For compilers that do not the level is just capped to the level they do support.


Support for language extensions

type Flag = String

extensionsToFlags :: Compiler -> [Extension] -> [Flag]

For the given compiler, return the flags for the supported extensions.

unsupportedExtensions :: Compiler -> [Extension] -> [Extension]

For the given compiler, return the extensions it does not support.

parmakeSupported :: Compiler -> Bool

Does this compiler support parallel --make mode?

reexportedModulesSupported :: Compiler -> Bool

Does this compiler support reexported-modules?

renamingPackageFlagsSupported :: Compiler -> Bool

Does this compiler support thinning/renaming on package flags?

unifiedIPIDRequired :: Compiler -> Bool

Does this compiler have unified IPIDs (so no package keys)

packageKeySupported :: Compiler -> Bool

Does this compiler support package keys?

unitIdSupported :: Compiler -> Bool

Does this compiler support unit IDs?

Support for profiling detail levels

data ProfDetailLevel

Some compilers (notably GHC) support profiling and can instrument programs so the system can account costs to different functions. There are different levels of detail that can be used for this accounting. For compilers that do not support this notion or the particular detail levels, this is either ignored or just capped to some similar level they do support.

knownProfDetailLevels :: [(String, [String], ProfDetailLevel)]