+(load "utils.scm")
+
(define (ast-type x)
(define (builtin? x)
(case x
('if 'if)
('let 'let)
('lambda 'lambda)
+ ('case 'case)
('closure 'closure) ; only available in codegen
('static-string 'static-string) ; only available in codegen
+ ('stack 'stack) ; only available in codegen (tag that value is passed via stack)
(else 'app)))
((builtin? x) 'builtin)
((symbol? x) 'var)
('app (map f x))
('lambda `(lambda ,(lambda-args x) ,(f (lambda-body x))))
('if `(if ,@(map f (cdr x))))
+ ('case `(case ,(f (case-switch x))
+ ,@(map (lambda (x)
+ (list (car x) (f (cadr x))))
+ (case-cases x))))
+ ('stack `(stack ,(cadr x) ,(f (caddr x))))
(else x)))
(define (ast-collect f x)
(inner (lambda-body x)))]
['if (append (f x)
(flat-map inner (cdr x)))]
+ ['case (append (f x)
+ (inner (case-switch x))
+ (flat-map inner (map cadr (case-cases x))))]
+ ['stack (append (f x)
+ (inner (caddr x)))]
[else (f x)]))
(define (ast-find p x)
['lambda (either (p x)
(inner (lambda-body x)))]
['if (either (p x) (any inner (cdr x)))]
+ ['stack (either (p x) (inner (caddr x)))]
[else (p x)]))
-(define (let-bindings e)
- (define (pattern-match x body)
- (if (eqv? (ast-type x) 'var)
- (cons x body)
- (let* ([constructor (car x)]
- [destructor (lambda (i) `(destruct ,i ,constructor))])
- (flat-map (lambda (y i)
- (pattern-match y (list (destructor i) body)))
- (cdr x)
- (range 0 (length (cdr x)))))))
- (flat-map (lambda (x) (pattern-match (car x) (cdr x))) (cadr e)))
+(define let-bindings cadr)
(define let-body cddr)
+(define case-switch cadr)
+(define case-cases cddr)
+
+;; (define (verify-cases data-layouts annotated-program)
+
+;; (define allowed-match-ast-types
+;; '((Int . (int-literal var))
+;; (Bool . (bool-literal var))
+;; (String . (string-literal var))))
+
+;; (define (check-pattern switch-type pat)
+
+;; (define (impossible-match)
+;; (error "Can't pattern match ~a with ~a" switch-type (ann-expr pat)))
+
+;; (if (assoc switch-type data-layouts)
+;; (begin
+;; (let ([sums (cdr (assoc switch-type data-layouts))])
+;; (unless (eqv? (ast-type (ann-expr pat)) 'var) (impossible-match))
+;; (unless (assoc (car (ann-expr pat)) sums) (impossible-match))
+;; (unless
+;; )
+;; (begin
+;; (unless (assoc switch-type allowed-match-ast-types)
+;; (error #f "Can't pattern match on ~a" switch-type))
+
+;; (let ([allowed (cdr (assoc switch-type allowed-match-ast-types))])
+;; (unless (assoc (ast-type (ann-expr pat)) allowed) (impossible-match)))))))
+
+
+;; (let ([expr (ann-expr annotated-program)])
+;; (case (ast-type expr)
+;; ['case
+;; (let* ([switch-type (ann-type (case-switch expr))]
+;; [allowed (cdr (assoc switch-type allowed-match-ast-types))])
+;; (for-each
+;; []))]))))
+
+
+ ; (let ([(foo a b) (foo 123 345)]) a)
+ ; |
+ ; v
+ ; (let ([a (foo~0 (foo 123 345)]
+ ; [b (foo~1 (foo 123 345)]) a)
+(define (expand-pattern-matches program)
+ (define (go x)
+ (define (let-pattern-match binding)
+ (let ([binding-name (car binding)]
+ [body (cadr binding)])
+ (if (eqv? (ast-type binding-name) 'var)
+ (list (list binding-name body))
+
+ (let* ([sum-name (car binding-name)]
+ [destructor (lambda (i) (dtor-name sum-name i))]
+ [products (cdr binding-name)]
+
+ [data-layouts (program-data-layouts program)]
+
+ [type (data-tor-type data-layouts sum-name)]
+
+ [sums (cdr (assoc type data-layouts))]
+ [sum (assoc sum-name sums)]
+
+ [expected-number (length (cdr sum))])
+
+ ; assert that we only do a let pattern match on an ADT with exactly one sum
+ (when (not (= 1 (length sums)))
+ (error #f (format "Cannot pattern match a ~a in a let since it has ~a possible constructors"
+ type
+ (length sums))))
+
+ ; assert that there is the correct number of bindings
+ (when (not (= (length products)
+ expected-number))
+ (error #f (format "Got ~a bindings: expected ~a for ~a"
+ (length products)
+ expected-number
+ binding)))
+
+ (flat-map (lambda (y i)
+ (let-pattern-match (list y `(,(destructor i) ,body))))
+ products
+ (range 0 (length products)))))))
+
+ (case (ast-type x)
+ ['let `(let ,(flat-map let-pattern-match (let-bindings x))
+ ,@(map go (let-body x)))]
+ [else (ast-traverse go x)]))
+ (program-map-exprs go program))
+
(define (lambda? x)
(and (list? x) (eq? (car x) 'lambda)))
-
(define (statement-type x)
(cond
[(and (list? x)
(eqv? (car x) 'define)) 'define]
[else 'expr]))
-(define (program-datas program)
- (filter (lambda (x) (eqv? (statement-type x) 'data))
- program))
+
+ ; (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))))
+
; 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 (references prog)
+ (ast-collect
+ (lambda (x)
+ (case (ast-type x)
+ ['var (list x)]
+ [else '()]))
+ prog))
+
+(define (graph bs)
+ (define (go bs orig-bs)
+ (if (null? bs)
+ '(() . ())
+ (let* [(bind (car bs))
+
+ (vert (car bind))
+ (refs (filter ; only count a reference if its a binding
+ (lambda (x) (assoc x orig-bs))
+ (references (cdr bind))))
+ (edges (map (lambda (x) (cons vert x))
+ refs))
+
+ (rest (if (null? (cdr bs))
+ (cons '() '())
+ (go (cdr bs) orig-bs)))
+ (total-verts (cons vert (car rest)))
+ (total-edges (append edges (cdr rest)))]
+ (cons total-verts total-edges))))
+ (go bs bs))
+
+(define (successors graph v)
+ (define (go v E)
+ (if (null? E)
+ '()
+ (if (eqv? v (caar E))
+ (cons (cdar E) (go v (cdr E)))
+ (go v (cdr E)))))
+ (go v (cdr graph)))
+
+ ; takes in a graph (pair of vertices, edges)
+ ; returns a list of strongly connected components
+
+ ; ((x y w) . ((x . y) (x . w) (w . x))
+
+ ; =>
+ ; .->x->y
+ ; | |
+ ; | v
+ ; .--w
+
+ ; ((x w) (y))
+
+ ; this uses tarjan's algorithm, to get reverse
+ ; topological sorting for free
+(define (sccs graph)
+
+ (let* ([indices (make-hash-table)]
+ [lowlinks (make-hash-table)]
+ [on-stack (make-hash-table)]
+ [current 0]
+ [stack '()]
+ [result '()])
-(define (flat-map f . xs) (fold-left append '() (map f xs)))
-(define (repeat x n) (if (<= n 0) '()
- (cons x (repeat x (- n 1)))))
+ (define (index v)
+ (get-hash-table indices v #f))
+ (define (lowlink v)
+ (get-hash-table lowlinks v #f))
+ (letrec
+ ([strong-connect
+ (lambda (v)
+ (begin
+ (put-hash-table! indices v current)
+ (put-hash-table! lowlinks v current)
+ (set! current (+ current 1))
+ (push! stack v)
+ (put-hash-table! on-stack v #t)
-(define-syntax push!
- (syntax-rules ()
- ((_ s x) (set! s (cons x s)))))
+ (for-each
+ (lambda (w)
+ (if (not (hashtable-contains? indices w))
+ ; successor w has not been visited, recurse
+ (begin
+ (strong-connect w)
+ (put-hash-table! lowlinks
+ v
+ (min (lowlink v) (lowlink w))))
+ ; successor w has been visited
+ (when (get-hash-table on-stack w #f)
+ (put-hash-table! lowlinks v (min (lowlink v) (index w))))))
+ (successors graph v))
-(define-syntax pop!
- (syntax-rules ()
- ((_ s) (let ([x (car s)])
- (set! s (cdr s))
- x))))
+ (when (= (index v) (lowlink v))
+ (let ([scc
+ (let new-scc ()
+ (let ([w (pop! stack)])
+ (put-hash-table! on-stack w #f)
+ (if (eqv? w v)
+ (list w)
+ (cons w (new-scc)))))])
+ (set! result (cons scc result))))))])
+ (for-each
+ (lambda (v)
+ (when (not (hashtable-contains? indices v)) ; v.index == -1
+ (strong-connect v)))
+ (car graph)))
+ result))