tail recursion optimisation

(TRO) When the last thing a function or procedure does is to

call itself, it is not necessary to retain the calling

environment. This is important when a procedure calls itself

recursively many times for, without tail recursion

optimisation, the environments of earlier invocations would

fill up the memory only to be discarded when (if) the last

call terminated.

Tail recursion optimisation is a special case of last calloptimisation but it allows the further optimisation that some

arguments may be passed in situ, possibly in registers. It

allows recursive functions to be compiled into iterative

loops. See also conversion to iteration, tail recursionmodulo cons.