Yi
Contents |
1 About
Yi is a text editor written in Haskell and extensible in Haskell. The goal of Yi is to provide a flexible, powerful and correct editor core scriptable in Haskell.
Features:
- A purely functional editor core;
- Keybindings written as parsers of the input;
- Emacs, Vim and Cua (subset) emulations provided by default;
- Vty, Gtk2Hs, and, in development, Cocoa and Pango frontends.
The long term goal of the project is to make Yi the editor of choice for the haskell hacker.
The main short term goal is to maximize Yi's Fun Factor. This includes:
- improve hackability (and therefore architecture)
- add cool features
former Yi homepage: http://www.cse.unsw.edu.au/~dons/yi.html
2 Get Yi
- Stable release on Hackage
- Development repository:
darcs get --lazy http://code.haskell.org/yi/
We now use the Darcs-2 repository format (to benefit from the improved performance and merge algorithms), so you will need Darcs 2.0 or higher to 'get' or 'pull'.
We try to keep the repository in a clean and buildable state, so it's "testable" for new users. Yi only supports ghc >= 6.10.
2.1 Yi for Mac OS X
The easiest way to get Yi for Mac OS X is currently no different from the above. There is also a very old deprecated Yi release in MacPorts. Please use the Hackage version instead.
Additionally, if you want a nice .app front-end you can download Yi.app (which does not contain Yi, it is just a wrapper, for now) and edit Yi.app/Contents/Resources/script if you did not use MacPorts to install Yi.
3 Screenshots (0.3)
4 News
There is a Yi blog, that reports the important news about Yi, at http://yi-editor.blogspot.com/. It also delves into algorithms and the Yi internals.
You can also check the /OldNews.
5 Bugs
Check/report bug reports here: Google Code: yi-editor
6 FAQs
6.1 Installation
- How do I install Yi?
- get it from Hackage. Configure, compile and install Yi as you would do for any other Cabal package.
- Setup configure fails with
Setup.hs: Package yi-0.4 can't be built on this system.
- It means that you have no UI package available. You need VTY or GTK2hs installed. Get them from Hackage.
- cabal install yi fails with dependency errors, eg:
$ cabal install yi Resolving dependencies... cabal.exe: dependencies conflict: ghc-6.8.3 requires bytestring ==0.9.0.1.1 however bytestring-0.9.0.1.1 was excluded because bytestring-0.9.0.1 was selected instead bytestring-0.9.0.1.1 was excluded because yi-0.3 requires bytestring =0.9.0.1
- Try removing all your old yi packages, and do
cabal update
before attempting to install.
- cabal install -fghcAPI fails
- If you want GHC API special capabilities, you have to download, configure, build and copy separately:
cd yi cabal configure -fghcAPI cabal build cabal copy
- Compilation fails with a message about alex not being available?
- Currently, Cabal doesn't track programs, just libraries, so it won't warn you if you are missing Alex (as many people are). The solution here is to just cabal install alex first. (Yi uses Alex to generate code for parsing stuff with syntax, like Haskell source.)
- I can't install yi-gtk or yi-vty! It wants sourceview or something.
- As the Hackage descriptions say, yi-gtk and yi-vty are only for versions of older than Yi 0.3. You really should be running the latest development (Darcs) or stable (Hackage) versions of Yi, so don't try to install these two packages. Yi supports VTY and Gtk2hs directly in the yi package now.
- On Mac OS X if you get an error message similar to this:
yi: can't load .so/.DLL for: gthread-2.0 (dlopen(libgthread-2.0.dylib, 10): image not found)
- then your dynamic library search path variable is probably not set correctly. You can set it (in Bash) using:
export DYLD_LIBRARY_PATH=/opt/local/lib
- (Adjust the specific path to your system. You can find the right location using locate libgthread)
6.1.1 Development
- How do I install Yi for development?
- Get it from http://code.haskell.org/yi while there are other repositories of Yi out there, this is the latest.
- What are some of the dependancies?
- The development version of Yi currently requires Cabal-1.4, fingertree-0.0, and utf8-string-0.3.1.
- If you are on Mac OS X and are using MacPorts, then these will not be included in the GHC in that distribution. Many of the dependancies are in MacPorts (for example: ghc, ghc-devel, alex, and gtk2hs). However, you may have some trouble building with Cabal-1.5.2, since it is a development version of Cabal. To work around these issues, you might have to add the line "Build-Type: Simple" to the .cabal files in the above required packages.
6.2 Configuration
6.2.1 How to Configure Yi
You can find configuration file examples in the 'examples/' directory, or online at http://code.haskell.org/yi/examples/.
A good way to start is to copy yi.hs in your ~/.yi directory (create it if needed), and hack as needed.
6.3 Usage
6.3.1 GError on startup
I get the error message "yi.exe: <<System.Glib.GError.GError>>" when I try to run yi.
Sometimes this is a result of yi not being able to find the contents of the art directory when trying to start in graphical mode (e.g. Gtk or Pango). Check that the install has be done correctly or use the VTY mode ($ yi -f vty).
For more detail on the error, modify main in Yi/Main.hs to catch GError:
Right finalCfg -> do catchGError (do
when (debugMode finalCfg) $ initDebug ".yi.dbg"
startEditor finalCfg state) (\(GError dom code msg) -> fail msg)
Note that more recent versions of Yi (e.g. from the darcs repo) no longer simply display the anonymous GError but instead provide a more detailed error message (making the above code snippet unnecessary).
7 Contribute
Get the repo here:
darcs get --partial http://code.haskell.org/yi/
Work on whatever you please, patches are always welcome. :)
Otherwise, see the complete list of open issues here: http://code.google.com/p/yi-editor/issues/list
(Note you can start working on all issues in New/Accepted state, regardless of the owner of the issue. -- you can send an email to the list with your plan if unsure)
Post your questions and follow up on the mailing list: http://groups.google.com/group/yi-devel
Some other pending tasks are described below.
7.1 Write access policy
One does not need write access to the repository to contribute. Use "darcs send" to send your patches to the Yi development mailing list; someone else can apply them.
Write access can however be granted, with the following disclaimer:
- All people with write access can apply patches without prior approval. If one thinks a patch would be controversial, it might be a good idea to discuss it on the list though.
- Try to not break the build. (By Murphy's law, if you do so it will happen at the most annoying moment...) So, always try to build before pushing patches. Bypassing Darcs's test build to record a patch indicates you should further improve your patch.
- I can at any time rollback a patch for whatever reason. This however should not upset the author of the patch. Most contributions are welcome, so a patch revert normally would only mean that a detail or two need to be worked out. (eg. it breaks an important feature in some configuration, etc.)
8 Yi ideas
This section is meant to gather ideas people have for Yi.
- Evolution to an IDE:
- Show exact location of compilation errors: 80% of an haskell project
- Support for the ghci debugger & others: 10 % of an haskell project (Added bonus: greath for learning: trough the debugger, people learn the real execution flow of an haskell program. Better if this is done inside an editor)
- Integration of refactoring tools : 5 %
- Edition: only 5%
- An extension to GHCi to support documentation of symbols.
- This seems to be (reasonably) straightforward, as GHCi already has :info. It would mean hacking the type environment (what about values?) to add documentation information. The main problem would seem to be populating this --- maybe hack haddock to produce something from the library docs? I assume that using package GHC uses the parent RTS (package GHC seems to be the way to go, but more investigation is required --- don?)
- Views on data
- Rather than just editing a file, you would open a view onto the file, i.e. there is no longer a 1-1 correspondence between buffers and files. Why? Well, for aggregate buffers (i.e., editing multiple files in the one view), or for multiple views of a file (e.g. AST and source-level). There would be some primitive ops for editing a buffer (insertChar, delete, etc.), which would then call update functions on anything observing that file.
- Remote attach so I can work from home, but still use a remote machine
- Like Emacs's server?
- Haddock documentation
- (no brainer), maybe associate with .hi files for binaries.
- Maybe a class
YiShow, which all config items must be a member of? This is to emulate describe-variable
- Support for collaborative editing. This would be very good for #haskell work, and the text editor Gobby and its Obby protocol seem to provide a candidate way of doing things.
8.1 Borrowing from other editors
Take some ideas from emacs, some from vi, but don't stick them all together without a single core philosophy. Otherwise, you'll end up with an editor that looks like it was thrown together. Some people come from an emacs background, some from vi, some from elsewhere, and ALL of them will want yi to behave like their regular editor. The best way to do this is to have a single person make all the decisions on behaviour.
8.1.1 Emacs
Coming from an Emacs background, I think a few things are essential, mainly the introspection capabilities of Emacs.
8.1.1.1 Emacs goodness
The following are things I like about Emacs, as an extensible environment, and miss in Yi:
- Really good online documentation
- Emacs can tell you a lot about a function or variable with a keypress--- the current value, where it is declared, and a hypertext formation string
- Hooks-Extensibility
- All (good) apps allow users to extend, through, e.g., hooks --- a list of functions that are run before/after some event (like saving a file)
- List of must-have features
- http://glyph.twistedmatrix.com/2008/12/emacs-test.html
8.1.1.2 Emacs badness
So, why replace it?:
- ELisp
- Dynamically scoped, Dynamically typed, ugly, old. 'Nuff said
- What's a Parser?
- A lot of apps in emacs do stuff with text, usually text that is in some language. There is no standard parser (like, e.g. parsec), so a lot of it is ugly handwritten spaghetti. This also means that adding analysis tools isn't really done (or done nicely).
- ELisp again
- Haskell is a lot cleaner to write, especially because of the large number of libraries.
(See also WhyDoesElispSuck on the Emacs wiki.)
8.1.1.3 Emacs maybeness (?)
Some things that are sometimes bad, sometimes good:
- Everything is a buffer
- Makes some sense, but sometimes doesn't. It is nice to have uniform key bindings do the right thing (e.g., C-Space sets the mark, and the region can then be used, e.g. to delete a sequence of emails in Wl) Sometimes, however, you just want some sort of GUI widget.
- OTOH, having the minibuffer be a special kind of buffer is a good idea.
- Properties
- It is possible to associate arbitrary properties with symbols. This means you can annotate a symbol and then use that information at a later date
8.1.2 Vim?
- good things
- modal key editing -> configuration system is powerful enough!
- light weight -> fast startup -> yi has this :)
8.2 Ideas
8.3 Implementation
Considerations:
- Interface to the runtime
- The scheduler, docs, etc.
- Introspection of e.g. what processes are running.
- There are already libraries in Haskell for processes, but they don't give Yi any extra information --- we really want a layer on top.
...
9 Trivia
- Y I is the most recursive acronym. (Read it as combinators).
- 義, pronounced yi, means righteousness, one of the five virtues of confucianism.
- Yi is the symbol for a yobi - the largest binary prefix, meaning 2^80