Cabal- A framework for packaging Haskell software

CopyrightIsaac Jones 2006, Duncan Coutts 2007-2009
Safe HaskellNone




This provides an abstraction which deals with configuring and running programs. A Program is a static notion of a known program. A ConfiguredProgram is a Program that has been found on the current machine and is ready to be run (possibly with some user-supplied default args). Configuring a program involves finding its location and if necessary finding its version. There's reasonable default behavior for trying to find "foo" in PATH, being able to override its location, etc.


Program and functions for constructing them

data Program Source

Represents a program which can be configured.

Note: rather than constructing this directly, start with simpleProgram and override any extra fields.




programName :: String

The simple name of the program, eg. ghc

programFindLocation :: Verbosity -> ProgramSearchPath -> IO (Maybe FilePath)

A function to search for the program if its location was not specified by the user. Usually this will just be a call to findProgramOnSearchPath.

It is supplied with the prevailing search path which will typically just be used as-is, but can be extended or ignored as needed.

programFindVersion :: Verbosity -> FilePath -> IO (Maybe Version)

Try to find the version of the program. For many programs this is not possible or is not necessary so it's ok to return Nothing.

programPostConf :: Verbosity -> ConfiguredProgram -> IO ConfiguredProgram

A function to do any additional configuration after we have located the program (and perhaps identified its version). For example it could add args, or environment vars.

type ProgramSearchPath = [ProgramSearchPathEntry] Source

A search path to use when locating executables. This is analogous to the unix $PATH or win32 %PATH% but with the ability to use the system default method for finding executables (findExecutable which on unix is simply looking on the $PATH but on win32 is a bit more complicated).

The default to use is [ProgSearchPathDefault] but you can add extra dirs either before, after or instead of the default, e.g. here we add an extra dir to search after the usual ones.

['ProgramSearchPathDefault', 'ProgramSearchPathDir' dir]

simpleProgram :: String -> Program Source

Make a simple named program.

By default we'll just search for it in the path and not try to find the version name. You can override these behaviours if necessary, eg:

simpleProgram "foo" { programFindLocation = ... , programFindVersion ... }

Configured program and related functions

data ConfiguredProgram Source

Represents a program which has been configured and is thus ready to be run.

These are usually made by configuring a Program, but if you have to construct one directly then start with simpleConfiguredProgram and override any extra fields.




programId :: String

Just the name again

programVersion :: Maybe Version

The version of this program, if it is known.

programDefaultArgs :: [String]

Default command-line args for this program. These flags will appear first on the command line, so they can be overridden by subsequent flags.

programOverrideArgs :: [String]

Override command-line args for this program. These flags will appear last on the command line, so they override all earlier flags.

programOverrideEnv :: [(String, Maybe String)]

Override environment variables for this program. These env vars will extend/override the prevailing environment of the current to form the environment for the new process.

programLocation :: ProgramLocation

Location of the program. eg. /usr/bin/ghc-6.4

programPath :: ConfiguredProgram -> FilePath Source

The full path of a configured program.

suppressOverrideArgs :: ConfiguredProgram -> ConfiguredProgram Source

Suppress any extra arguments added by the user.

data ProgramLocation Source

Where a program was found. Also tells us whether it's specifed by user or not. This includes not just the path, but the program as well.



The user gave the path to this program, eg. --ghc-path=/usr/bin/ghc-6.6


The program was found automatically.

simpleConfiguredProgram :: String -> ProgramLocation -> ConfiguredProgram Source

Make a simple ConfiguredProgram.

simpleConfiguredProgram "foo" (FoundOnSystem path)