Following-up a link about Haskell, http://www.jsoftware.com/pipermail/chat/2010-January/002928.html
I found there is an Eclipse IDE for it, which uses an Eclipse API to integrate other languages http://eclipsefp.sourceforge.net/ which relies on common IDE layer in a particular Haskell system GHC http://code.google.com/p/scion-lib/ which among other things provides Emacs support. So these are some good ideas how to optimize dealing with third-party IDEs, or maybe even to organize a native IDE. ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
