Implemention of reduction based evaluation of lambda calculus expressions. ;;; Abstract Syntax for the LAMBDA CALCULUS ;;; ======================================= ;;; <ast> ::= ;;; ;;; <id-ref-ast> | ;;; <function-ast> | ;;; <app-ast> ;;; <function-ast> ::= (function <id> <ast>) ;;; <app-ast> ::= (app <ast> <ast> )