Functional Programming, Haskell, Computer Science, Lambda Calculus, Algorithms.
merely redirect the reference of var to point to arg. That makes application a constant-time operation! As an example, here is the full execution of fst (1, 2): (λp. p (λa. λb. a)) (λt. t 1 2) ------------------------------- lambda application (λt. t 1 2) (λa. λb. a) ----------------------- lambda