The fexpr idea is at the very heart of Lisp, which I think makes it truly transposable to other paradigms. Alan Kay credits the fexpr as one of the inspirations

The fexpr idea is at the very heart of Lisp, which I think makes it truly transposable to other paradigms. Alan Kay credits the fexpr as one of the inspirations for Smalltalk[0] taken from Lisp: > My next question was, why on earth call it a functional language? Why not just base everything on FEXPRs and force evaluation on the receiving side when needed? I could never get a good answer, but the question was very helpful when it came time to invent Smalltalk, because this started a line of thought that said "take the hardest and most profound thing you need to do, make it great, and then build every easier thing out of it". That was the promise of LISP and the lure of lambda—needed was a better "hardest and most profound" thing. Objects should be it. You can see the basic idea for the Vau calculus in that quote. Shutt (RIP)[1] later elaborated the theory and proved they were not "trivial" and anathema to compilation [2]. It's great to see new interpretations and uses of the fexpr! [0] http://worrydream.com/EarlyHistoryOfSmalltalk/ http://worrydream.com/EarlyHistoryOfSmalltalk/ [1] https://en.wikinews.org/wiki/Wikinews_mourns_loss_of_volunteer_John_Shutt https://en.wikinews.org/wiki/Wikinews_mourns_loss_of_volunte... [2] https://fexpr.blogspot.com/2011/04/fexpr.html https://fexpr.blogspot.com/2011/04/fexpr.html