Thanks for your response. > When not all call sites can be found (for example in compilation of separate files), it is still possible to create two versions of

Thanks for your response. > When not all call sites can be found (for example in compilation of separate files), it is still possible to create two versions of (ADDER x), one that uses lambda lifting and one that does not. I'm starting to suspect we interpreted the original comment ("getting rid of closures") differently. I understood that as completely eliminating all closures from a source program via lambda lifting, such that an implementation needs no alternative method of implementing closures. It sounds like maybe you understood that as getting rid of a specific occurrence of a closure in certain special cases, more like an optimization. Does that sound accurate? I can imagine several scenarios when it seems like you could have have a closure that could not be eliminated via lambda lifting (like maybe if the identity of the returned function is nondeterministic, or where the closure includes some mutable state called from multiple sites). Put another way, does your implementation have lambda lifting in addition to a runtime implementation of closures, or instead of one. Can lambda lifting completely obviate the need for passing around an environment in all cases, or just optimize it away in certain cases?