Hi,
On Wed, Oct 25, 2000 at 09:03:43AM -0700, Doug Ransom wrote:
I would like to be able to inspect the type of things easily by hovering my mouse over an expression. As a beginner, I find it hard sometimes to get types correct in Haskell since often variables are not declared as a specific type.
Since you are typically dealing with incomplete programs in an editor this is really tough. The PSG system was able to generate such editors and I once saw it for the purely functional language Sample in action: you could mark any term with the mouse cursor and ask for its type.
One of the emacs modes for Haskell gives the type of the identifier the cursor is in in the modeline. It does this by examining the type signatures in the current file, and having the prelude type signatures built-in. This is quite helpful, if incomplete, and fairly easy to implement.
To increase its usefulness for multi-module programs, I have been planning for a long time to extract type info out of .hi files and feed it into the haskell-doc emacs module. Well, one day I may write an elisp parser to do that. In the meantime there is of course the possibility of pre-processing the Haskell source (or .hi) and feeding the type info as an elisp expression directly to haskell-doc. Here is the relevant bit from the docu: ;; If you want to define your own strings for some identifiers define an ;; alist of (ID . STRING) and set `haskell-doc-show-user-defined' to t. ;; E.g: ;; ;; (setq haskell-doc-show-user-defined t) ;; (setq haskell-doc-user-defined-ids ;; (list ;; '("main" . "just another pathetic main function") ;; '("foo" . "a very dummy name") ;; '("bar" . "another dummy name"))) Hope that helps, -- Hans Wolfgang