# ghc-imported-from
For a given Haskell source file, determine the path to the Haddock documentation for a symbol at a particular line/col location.
Example: on the file [src/Main.hs](https://github.com/carlohamalainen/ghc-imported-from/blob/master/src/Main.hs),
ghc-imported-from haddock-url src/Main.hs Main getArgs 69 13
says
SUCCESS: file:///home/carlo/opt/ghc-7.6.3_build/share/doc/ghc/html/libraries/base-4.6.0.1/System-Environment.html
since the usage of ```getArgs``` at line 160, column 13, is from the ```System.Environment``` module.
Difficulties arise because some symbols are exported from a certain
package but defined in another, for example ```String``` is defined in
```GHC.Base``` but is exported from the standard prelude, the module
```Prelude```. There are other cases to deal with including qualified
imports, selective imports, imports with hidden components, etc.
Preference is given to any locally available Haddock documentation,
and then to the generic url at hackage.org.
## Beware
You may have to run
cabal build
or
cabal repl
in a project directory to sort out some of the ```dist/build/autogen```
files. At the moment ```ghc-imported-from``` has no functionality to
do this boot process automatically. To run ```cabal repl``` you might need
the latest Cabal from [https://github.com/haskell/cabal](https://github.com/haskell/cabal).
If you see
<command line>: cannot satisfy -package hspec
(use -v for more information)
then you may need the hspec and/or doctest packages:
cabal install hspec doctest
Feedback and pull requests most welcome!
## Install
### ghc-imported-from
Install into ```~/.cabal```:
git clone https://github.com/carlohamalainen/ghc-imported-from
cd ghc-imported-from
cabal install
Or, install into a sandbox:
git clone https://github.com/carlohamalainen/ghc-imported-from
cd ghc-imported-from
./build_in_sandbox.sh
Either way, ensure that ```ghc-imported-from``` is in the current PATH.
### ghcimportedfrom-vim
Follow the instructions at
[https://github.com/carlohamalainen/ghcimportedfrom-vim](https://github.com/carlohamalainen/ghcimportedfrom-vim)
to install the Vim plugin.
## Usage
See the ```tests``` subdirectory for some examples. Or load your favourite Haskell project and hit F4.
Or watch the screencast (be sure to set 720p HD and then fullscreen):
[http://www.youtube.com/watch?v=VVc8uupYJGs](http://www.youtube.com/watch?v=VVc8uupYJGs)