Cabal- A framework for packaging Haskell software

CopyrightDuncan Coutts 2009
Safe HaskellNone



This module provides a data type for program invocations and functions to run them.



data ProgramInvocation Source #

Represents a specific invocation of a specific program.

This is used as an intermediate type between deciding how to call a program and actually doing it. This provides the opportunity to the caller to adjust how the program will be called. These invocations can either be run directly or turned into shell or batch scripts.

multiStageProgramInvocation :: ProgramInvocation -> (ProgramInvocation, ProgramInvocation, ProgramInvocation) -> [String] -> [ProgramInvocation] Source #

Like the unix xargs program. Useful for when we've got very long command lines that might overflow an OS limit on command line length and so you need to invoke a command multiple times to get all the args in.

It takes four template invocations corresponding to the simple, initial, middle and last invocations. If the number of args given is small enough that we can get away with just a single invocation then the simple one is used:

$ simple args

If the number of args given means that we need to use multiple invocations then the templates for the initial, middle and last invocations are used:

$ initial args_0
$ middle  args_1
$ middle  args_2
$ final   args_n

getEffectiveEnvironment :: [(String, Maybe String)] -> NoCallStackIO (Maybe [(String, String)]) Source #

Return the current environment extended with the given overrides. If an entry is specified twice in overrides, the second entry takes precedence.