-(define (app? x)
- (and (list? x)
- (>= (length x) 2)
- (not (eq? (car x) 'let))
- (not (eq? (car x) 'lambda))))
+(define (ast-type x)
+ (define (builtin? x)
+ (case x
+ ('+ #t)
+ ('- #t)
+ ('* #t)
+ ('! #t)
+ ('= #t)
+ ('bool->int #t)
+ ('print #t)
+ (else #f)))
+ (cond
+ ((list? x)
+ (case (car x)
+ ('if 'if)
+ ('let 'let)
+ ('lambda 'lambda)
+ ('closure 'closure) ; only available in codegen
+ ('static-string 'static-string) ; only available in codegen
+ (else 'app)))
+ ((builtin? x) 'builtin)
+ ((symbol? x) 'var)
+ ((integer? x) 'int-literal)
+ ((boolean? x) 'bool-literal)
+ ((string? x) 'string-literal)))
-(define (let? x)
- (and (list? x) (eq? (car x) 'let)))
+(define (ast-traverse f x)
+ (case (ast-type x)
+ ('let `(let ,(map (lambda (x) (list (car x) (f (cadr x))))
+ (let-bindings x))
+ ,@(map f (let-body x))))
+ ('app (map f x))
+ ('lambda `(lambda ,(lambda-args x) ,(f (lambda-body x))))
+ ('if `(if ,@(map f (cdr x))))
+ (else x)))
(define let-bindings cadr)
(define let-body cddr)
(define (lambda? x)
(and (list? x) (eq? (car x) 'lambda)))
-(define lambda-arg cadr)
-(define lambda-body cddr)
-
-(define (var? x)
- (and (not (list? x)) (symbol? x)))
+; for use in normalized form
+(define lambda-arg caadr)
+; for use elsewhere
+(define lambda-args cadr)
+(define lambda-body caddr)