From: Ramakrishnan Muthukrishnan Date: Fri, 9 Dec 2011 21:21:22 +0000 (+0530) Subject: changes in the metacircular eval for primitive procedures X-Git-Url: https://git.rkrishnan.org/%5B/%5D%20/uri/%22doc.html/?a=commitdiff_plain;h=91494e6f42e823aa5b7114bdd91e394dd46d5051;p=sicp.git changes in the metacircular eval for primitive procedures --- diff --git a/src/sicp/metacircular.rkt b/src/sicp/metacircular.rkt index bae6128..ac37698 100644 --- a/src/sicp/metacircular.rkt +++ b/src/sicp/metacircular.rkt @@ -1,6 +1,6 @@ -#lang racket +#lang planet neil/sicp -(require "ex4_8.rkt" ;; for let and named let +(#%require "ex4_8.rkt" ;; for let and named let "ex4_7.rkt") ;; metacircular evaluator @@ -25,6 +25,9 @@ (else (error "unknown expression type -- EVAL" exp)))) +;; capture the underlying apply before redefining it +(define apply-in-underlying-scheme apply) + (define (apply procedure arguments) (cond ((primitive-procedure? procedure) (apply-primitive-procedure procedure arguments)) @@ -146,7 +149,7 @@ (define (begin-actions exp) (cdr exp)) (define (last-exp? seq) (null? (cdr seq))) (define (first-exp seq) (car seq)) -(define (rest-exp seq) (cdr seq)) +(define (rest-exps seq) (cdr seq)) (define (sequence->exp seq) (cond ((null? seq) seq) @@ -202,7 +205,7 @@ (define (procedure-parameters p) (cadr p)) (define (procedure-body p) (caddr p)) -(define (procedure-env p) (cadddr p)) +(define (procedure-environment p) (cadddr p)) ;; operations on environment (define (enclosing-environment env) (cdr env)) @@ -267,3 +270,44 @@ (scan (frame-variables frame) (frame-values frame)))) + +;; primitive procedures +(define (primitive-procedure? proc) + (tagged-list? proc 'primitive)) + +(define (primitive-implementation proc) (cadr proc)) + +(define primitive-procedures + (list (list 'car car) + (list 'cdr cdr) + (list 'cons cons) + (list 'null? null?) + (list '+ +) + (list '- -) + (list '= =))) + +(define (primitive-procedure-names) + (map car primitive-procedures)) + +(define (primitive-procedure-objects) + (map (lambda (proc) (list 'primitive (cadr proc))) + primitive-procedures)) + +;; apply from implementation language +(define (apply-primitive-procedure proc args) + (apply-in-underlying-scheme + (primitive-implementation proc) args)) + +;; setting up the environment +(define (setup-environment) + (let ((initial-env + (extend-environment (primitive-procedure-names) + (primitive-procedure-objects) + the-empty-environment))) + (define-variable! 'true #t initial-env) + (define-variable! 'false #f initial-env) + initial-env)) + +(define the-global-environment (setup-environment)) + +