How do you use Lisp functions in Haskell code? This is what I have tried: In a file name test.hs, I write module Main where import Add main = print (add 1 2) In a file name test.hu, I write interface Add where add :: Int->Int->Int {-# add :: LispName("user:add") #-} And in a file name test.lisp, I write (in-package 'user) (defun add (x y) (the fixnum (+ (the fixnum x) (the fixnum y)))) I am using the emacs Haskell user interface. In emacs, I do a C-x C-f to find file t1.hs, then I do C-c m to run the main module. The response I got is: file extension for {-# add :: LispName("user:add") #-} is needed. What do I need to do to accomplish the task? ------------------------------------------- Also, page 2 of Haskell Users Manual, last bullet item at middle of page says "We do not handle interface files yet." Does that has anything to do with what I'm trying to do above?