Ryan Ingram wrote:
What are you trying to get from the "let" binding? Sharing?
Convinience. let x = foo in bar is so much easier to write than (\x -> bar) foo when foo and/or bar is large. Trouble is, as soon as you allow let-bindings, some clever person is going to start writing recursive ones. And actually, that's a useful thing to be able to do, but it makes figuring out the technical details... rather nontrivial. (Seriously, I had no idea I was going to get into this much trouble!)
The usual idea is that "let" represents heap allocation, and you evaluate the leftmost-outermost redex as usual, doing let substitution only when necessary to continue evaluation, and garbage-collecting bindings that no longer refer to variables in the current computation
Right. So ignore the let-bindings unless the redex of interest is a let-bound variable? That sounds reasonably easy...