chickadee » sicp » eval*

The SICP implementation of eval; had to rename it eval*, because the redefinition of eval wrought havok on the module-system.

exp

The expression to evaluate

env

The environment to evaluate it in

(define (eval* exp env)
  (cond ((self-evaluating? exp) exp)
        ((variable? exp) (lookup-variable-value exp env))
        ((quoted? exp) (text-of-quotation exp))
        ((assignment? exp) (eval-assignment exp env))
        ((definition? exp) (eval-definition exp env))
        ((if? exp) (eval-if exp env))
        ((lambda? exp)
         (make-procedure (lambda-parameters exp) (lambda-body exp) env))
        ((begin? exp) (eval-sequence (begin-actions exp) env))
        ((cond? exp) (eval* (cond->if exp) env))
        ((application? exp)
         (apply*
           (eval* (operator exp) env)
           (list-of-values (operands exp) env)))
        (else (error "Unknown expression type: EVAL" exp))))