The syntax is close to Scheme and with small changes will run in a Scheme interpreter. For example, here's a session at the REPL of Racket: ~$ racket Welco

The syntax is close to Scheme and with small changes will run in a Scheme interpreter. For example, here's a session at the REPL of Racket: ~$ racket Welcome to Racket v7.2.0.6. > (define True (lambda (t f) (t))) > (define False (lambda (t f) (f))) > (define If (lambda (b tr fa) (b tr fa))) > (define P (lambda (x) (If x (lambda () (display "It was true!")) (lambda () (display "It was false!"))))) > (P True) It was true! > (P False) It was false! > Seen differently, it's also close to the mathematical notation of the lambda calculus. To learn about the lambda calculus, check out chapter 5 of "Types and Programming Languages", Benjamin C. Pierce, MIT Press 2002. You might also get something out of "Semantics Engineering with PLT Redex", Felleisen, Findler & Flatt, MIT Press 2009.