+(define (statement-type x)
+ (cond
+ [(and (list? x)
+ (eqv? (car x) 'data)) 'data]
+ [(and (list? x)
+ (eqv? (car x) 'define)) 'define]
+ [else 'expr]))
+
+
+ ; (A ((foo (Int Bool))
+ ; (bar (Bool)))
+(define (program-data-layouts program)
+ (map (lambda (x) (cons (car x) (cdr x))) ; convert to assoc list
+ (map cdr (filter (lambda (x) (eqv? (statement-type x) 'data))
+ program))))
+
+(define (program-defines program)
+ (filter (lambda (x) (eqv? (statement-type x) 'defines))
+ program))
+
+(define (program-map-exprs f program)
+ (map (lambda (x)
+ (case (statement-type x)
+ ['expr (f x)]
+ [else x]))
+ program))
+
+(define (program-body program)
+ ; hack to have multi-expression bodies
+ `(let ()
+ ,@(filter (lambda (x) (eqv? (statement-type x) 'expr))
+ program)))
+
+(define (data-tor-type data-layouts tor)
+ (let* ([tors (flat-map data-tors data-layouts)]
+ [info (cadr (assoc tor tors))])
+ (car info)))
+
+ ; a data tor is either a constructor or destructor for an ADT
+ ; data-tors returns constructors and destructors for a data-layout
+ ; (data A (foo Int Bool)
+ ; (bar Bool))
+ ; |
+ ; v
+ ; (foo . ((A foo constructor) . (abs Int (abs Bool A))))
+ ; (foo~0 . ((A foo 0 Int) . (abs A Int)))
+ ; (foo~1 . ((A foo 1 Bool) . (abs A Bool)))
+ ; (bar . ((A bar constructor) . (abs Bool A)))
+ ; (bar~0 . ((A bar 0 Bool) . (abs A Bool)))
+ ; ------+-------------------------------------
+ ; tor | info | type
+
+(define (data-tors data-layout)
+ (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)]
+ [info (list prod-type ctor-name index part-type)])
+ (cons name (cons info `(abs ,prod-type ,part-type)))))
+
+ (let ([type-name (car data-layout)]
+ [ctors (cdr data-layout)])
+ (fold-right
+ (lambda (ctor acc)
+ (let* ([ctor-name (car ctor)]
+ [products (cdr ctor)]
+
+ [maker (cons ctor-name (cons (list type-name ctor-name 'constructor) (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))))
+ '()
+ ctors)))
+
+ ; creates a type environment for a given adt definition
+(define (data-tors-type-env data-layout)
+ (map (lambda (x) (cons (car x) (cddr x))) (data-tors data-layout)))
+
+(define (dtor-name ctor-name index)
+ (string->symbol
+ (string-append (symbol->string ctor-name)
+ "~"
+ (number->string index))))
+