John Backus' FP language interpreter (together with denotational semantics for the language)
This project includes both GUI front end for the interpreter and REPL command-line front-end.
Sample functions in John Backus' "program algebra" style:
factorial definition in "program algebra" style:
DEF factNonRecursive = INSERT-RIGHT * . iota
factorial definition in lambda calculus style:
DEF fact = (eq0 -> ~1; * . [id, fact . s])
length definition in "program algebra" style:
DEF length = INSERT-RIGHT + . APPLY-ALL ~1
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