P.S.: I am willing to help you with the sample implementation if you want to incorporate some of my suggestions (e.g. "_" is position 3 or later, or to code the "let"-wrappers) and if you don't like macro programming too much (or take a look at SRFI 148, which makes programming or powerful macros very easy).I think can deal with "let" wrappers rather easily, but I'd love to see a straightforwardsolution for "_" in position 3 or later (I have an idea how to do this with syntax-rules,but it would require an auxiliary macro to decide whether the "_" symbol appears
anywhere in the expression. It's not very complex, but I'm not sure whether it isactually worth it)