On 21-feb-2007, at 20:18, Claus Reinke wrote:
The good reason is that you do not actually want to have to specify all the options that you need to get your program to compile, merely to get tag information. To generate the tags for dazzle using ghci I need to use echo ":ctags"| ghci -v0 Main.hs -i../lib -i../lib/DData/ - fglasgow-exts -L../ -lsmilec whereas with hasktags I'd just use hasktags *.hs
yes, that's a general problem with using ghci in real projects. of course, *.hs isn't always sufficient to find the files for a project, and the files might need pre-processing, etc. but there are advantages to not having a proper parser and just treating a project as a collection of files, to be found by globbing or find, and to be scanned for some simple patterns. it means that one can get tags for incomplete projects, even with errors in the files.
I fully concur. And the examples I gave do in fact work for the code
for Dazzle (some 14000 loc). hasktags is quite a bit faster than ghci
as well.
What I would *really* like is a Haskell parser in Exuberant Ctags... that would mean I could directly use vim's taglist extension.
another good point, but:
exuberant ctags is just another tagfile generator. it is very good for other languages, but *really* teaching it about Haskell is non-trivial. whereas ghci or ghc-api already know how to type things and all the rest of Haskell's static semantics, in addition to parsing things..
My current thoughts lean toward linking exuberant ctags with ghc-api in JustTypecheck mode, which would give me huge flexibility, allowing for e.g. multiple-language projects including Haskell code (one thing I didn't mention is that Dazzle builds against a C library... :)).
as for using taglist: do you mean the vim function taglist, which gives you a dictionary with information associated with a tag? so you are probably interested in extra information about tags, beyond source location. (*)
I meant http://vim-taglist.sourceforge.net/ which provides a neat interface and some extra convenience. It is somewhat dependent on exuberant ctags.
it should be a lot easier to expand the information generated by :ctags than to add a Haskell parser/type checker to exuberant ctags. the format is simply a comment (to protect old vi from choking on the extra info) followed by a list of extra fields (the dictionary) for each tag. see ":help tags-file-format" in vim, the third variant of the format.
I understand the tags file format. My vim fu is not as strong yours, but I have been using vim since it was at version 4.something and run into wanting to improve the tags at my disposal before. One of the things a custom tag generator could do is generate not just hardcoded locations in the tags file, but search patterns. This should make the tags file itself quite a bit more robust against changes, thereby obviating much of the need for dynamic regeneration.
have a look at ghc/compiler/ghci/InteractiveUI.hs, around listTags/ TagInfo. if one knows where to get it, one could add info there (eg, the type of the tag, or whether the tag is a type/class/function/module/ whatever). and the extra info ought to be written to the tags file, in collateAndWriteTags (simply ignore the extra info when writing the emacs tag file).
Thanks for the pointer, I'll look into it.
(*) if you want to go for broke, try ":help cursorhold-example" in vim. that will keep a preview window with the source-location of any tag your cursor remains on for long enough. so you might see the type declaration, or you might see the data type constructors belonging to a type, or .. i haven't used this as a default myself, but it is worth looking at at least once!-)
Hm. This would actually be much more useful if it were to follow the Visual Haskell method where hovering over a selection will show you the type of the selected subexpression. Good ideas sprouting again... pity it's almost bedtime. :) Doei, Arthur. -- /\ / | arthurvl@cs.uu.nl | Work like you don't need the money /__\ / | A friend is someone with whom | Love like you have never been hurt / \/__ | you can dare to be yourself | Dance like there's nobody watching