+(define (statement-type x)
+ (cond
+ [(and (list? x)
+ (eqv? (car x) 'data)) 'data]
+ [(and (list? x)
+ (eqv? (car x) 'define)) 'define]
+ [else 'expr]))
+
+(define (program-datas program)
+ (filter (lambda (x) (eqv? (statement-type x) 'data))
+ program))
+
+(define (program-defines program)
+ (filter (lambda (x) (eqv? (statement-type x) 'defines))
+ program))
+
+(define (program-body program)
+ `(let ()
+ ,@(filter (lambda (x) (eqv? (statement-type x) 'expr))
+ program)))
+
+ ; gets both constructors and destructors
+ ; (data A (foo Int Bool)
+ ; (bar Bool))
+ ; |
+ ; v
+ ; (foo . (abs Int (abs Bool A)))
+ ; (foo~0 . (abs A Int)
+ ; (foo~1 . (abs A Bool)
+ ; (bar . (abs Bool A)
+ ; (bar~0 . (abs A Bool)
+
+(define (data-tors data-def)
+ (define (constructor-type t products)
+ (fold-right (lambda (x acc) `(abs ,x ,acc)) t products))
+
+ (define (destructor ctor-name prod-type part-type index)
+ (let ([name (dtor-name ctor-name index)])
+ (cons name `(abs ,prod-type ,part-type))))
+
+ (let ([type-name (cadr data-def)]
+ [ctors (cddr data-def)])
+ (fold-right
+ (lambda (ctor acc)
+ (let* ([ctor-name (car ctor)]
+ [products (cdr ctor)]
+
+ [maker (cons ctor-name (constructor-type type-name products))]
+
+ [dtors (map (lambda (t i) (destructor ctor-name type-name t i))
+ products
+ (range 0 (length products)))])
+
+ (cons maker (append dtors acc))))
+ '()
+ ctrs)))
+
+(define (dtor-name ctor-name index)
+ (string->symbol
+ (string-append (symbol->string ctor-name)
+ "~"
+ (number->string index))))
+
+; for use in normalized form
+(define lambda-arg caadr)
+; for use elsewhere
+(define lambda-args cadr)
+(define lambda-body caddr)
+
+ ; utils
+(define (range s n)
+ (if (= 0 n) '()
+ (append (range s (- n 1))
+ (list (+ s (- n 1))))))
+
+(define (flat-map f . xs) (fold-left append '() (apply map (cons f xs))))
+(define (repeat x n) (if (<= n 0) '()
+ (cons x (repeat x (- n 1)))))
+
+
+(define-syntax push!
+ (syntax-rules ()
+ ((_ s x) (set! s (cons x s)))))
+
+(define-syntax pop!
+ (syntax-rules ()
+ ((_ s) (let ([x (car s)])
+ (set! s (cdr s))
+ x))))