X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=docs%2Fusers_guide%2Fpackages.xml;fp=docs%2Fusers_guide%2Fpackages.xml;h=7c934a2f45f77eaa93976f7a59efa83ac8a78fbd;hb=6dcff14bc5a7b394cf77f98b369d6f93c030cb36;hp=f209d57b5af0a8ab718e6448931d1c448e79a95d;hpb=f5f43a8ed4199e1251aa0e02cafb0acd14ff4535;p=ghc-hetmet.git
diff --git a/docs/users_guide/packages.xml b/docs/users_guide/packages.xml
index f209d57..7c934a2 100644
--- a/docs/users_guide/packages.xml
+++ b/docs/users_guide/packages.xml
@@ -30,49 +30,15 @@ Packages
packagesusing
- To see which packages are installed, use the
- ghc-pkg command:
+ GHC only knows about packages that are installed.
-
-$ ghc-pkg list
-/usr/lib/ghc-6.4/package.conf:
- base-1.0, haskell98-1.0, template-haskell-1.0, mtl-1.0, unix-1.0,
- Cabal-1.0, haskell-src-1.0, parsec-1.0, network-1.0,
- QuickCheck-1.0, HUnit-1.1, fgl-1.0, X11-1.1, HGL-3.1, OpenGL-2.0,
- GLUT-2.0, stm-1.0, readline-1.0, (lang-1.0), (concurrent-1.0),
- (posix-1.0), (util-1.0), (data-1.0), (text-1.0), (net-1.0),
- (hssource-1.0), rts-1.0
-
-
- Packages are either exposed or hidden. Only
- modules from exposed packages may be imported by your Haskell code; if
+ An installed package is either exposed or hidden
+ by default. Command-line flags, described below, allow you to expose a hidden package
+ or hide an exposed one.
+ Only modules from exposed packages may be imported by your Haskell code; if
you try to import a module from a hidden package, GHC will emit an error
message.
- Each package has an exposed flag, which says whether it is exposed by
- default or not. Packages hidden by default are listed in
- parentheses (eg. (lang-1.0)) in the output from
- ghc-pkg list. To expose a package which is hidden by
- default, use the
- flag (see below).
-
- To see which modules are exposed by a package:
-
-
-$ ghc-pkg field network exposed-modules
-exposed-modules: Network.BSD,
- Network.CGI,
- Network.Socket,
- Network.URI,
- Network
-
-
- In general, packages containing hierarchical modules are usually
- exposed by default. However, it is possible for two packages to contain
- the same module: in this case, only one of the packages should be
- exposed. It is an error to import a module that belongs to more than one
- exposed package.
-
The GHC command line options that control packages are:
@@ -82,7 +48,7 @@ exposed-modules: Network.BSD,
- This option causes package P to be
+ This option causes the installed package P to be
exposed. The package P can be specified
in full with its version number
(e.g. network-1.0) or the version number can be
@@ -180,7 +146,81 @@ exposed-modules: Network.BSD,
useful.
+
+
+ foo
+
+
+
+ Tells GHC the the module being compiled forms part of
+ package foo.
+ If this flag is omitted (a very common case) then the
+ default package main is assumed.
+ Note: the argument to
+ should be the full package identifier for the package,
+ that is it should include the version number. For example:
+ -package mypkg-1.2.
+
+
+
+
+ To see which packages are installed, use the
+ ghc-pkg command:
+
+
+$ ghc-pkg list
+/usr/lib/ghc-6.4/package.conf:
+ base-1.0, haskell98-1.0, template-haskell-1.0, mtl-1.0, unix-1.0,
+ Cabal-1.0, haskell-src-1.0, parsec-1.0, network-1.0,
+ QuickCheck-1.0, HUnit-1.1, fgl-1.0, X11-1.1, HGL-3.1, OpenGL-2.0,
+ GLUT-2.0, stm-1.0, readline-1.0, (lang-1.0), (concurrent-1.0),
+ (posix-1.0), (util-1.0), (data-1.0), (text-1.0), (net-1.0),
+ (hssource-1.0), rts-1.0
+
+
+ Packages hidden by default are listed in
+ parentheses (eg. (lang-1.0)) in the output above.
+ To expose a package which is hidden by
+ default, use the
+ flag (see above).
+
+ When a package is exposed, it makes available for import the exposed modules
+ of the package. To see which modules are exposed by a package use the
+ ghc-pkg command (see ):
+
+
+$ ghc-pkg field network exposed-modules
+exposed-modules: Network.BSD,
+ Network.CGI,
+ Network.Socket,
+ Network.URI,
+ Network
+
+
+ In general, packages containing hierarchical modules are usually
+ exposed by default. However, it is possible for two packages to contain
+ the same module: in this case, only one of the packages should be
+ exposed. It is an error to import a module that belongs to more than one
+ exposed package.
+
+
+
+
+ The main package
+
+ Every complete Haskell program must define main in
+ module Main
+ in package main. (Omitting the flag compiles
+ code for package main.) Failure to do so leads to a somewhat obscure
+ link-time error of the form:
+
+/usr/bin/ld: Undefined symbols:
+_ZCMain_main_closure
+___stginit_ZCMain
+
+
+
@@ -243,7 +283,7 @@ exposed-modules: Network.BSD,
database will override those of the same name in the global
database.
- You can control the loading of package databses using the following
+ You can control the loading of package databases using the following
GHC options:
@@ -379,28 +419,8 @@ $ export GHC_PACKAGE_PATH=$HOME/.my-ghc-packages.conf:
To compile a module which is to be part of a new package,
- use the -package-name option:
-
-
-
-
- -package-name
- option
-
- This option is added to the command line when
- compiling a module that is destined to be part of package
- foo. If this flag is omitted then the
- default package main is assumed.
-
- Note: the argument to
- should be the full package identifier for the package,
- that is it should include the version number. For example:
- -package mypkg-1.2.
-
-
-
-
- Failure to use the -package-name option
+ use the -package-name option ().
+ Failure to use the -package-name option
when compiling a package will probably result in disaster, but
you will only discover later when you attempt to import modules
from the package. At this point GHC will complain that the