(load "utils.scm") (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) ('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) ((integer? x) 'int-literal) ((string? x) 'string-literal))) (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)))) ('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) (define (inner y) (ast-collect f y)) (case (ast-type x) ['let (append (f x) (flat-map inner (let-bindings x)) (flat-map inner (let-body x)))] ['app (append (f x) (flat-map inner x))] ['lambda (append (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) (define (inner y) (ast-find p y)) (case (ast-type x) ['let (or (p x) (any inner (let-bindings x)) (any inner (let-body x)))] ['app (or (p x) (any inner x))] ['lambda (or (p x) (inner (lambda-body x)))] ['if (or (p x) (any inner (cdr x)))] ['case (or (p x) (any inner (map cadr (case-cases x))) (inner (case-switch x)))] ['stack (or (p x) (inner (caddr x)))] [else (p x)])) (define let-bindings cadr) (define let-body cddr) (define case-switch cadr) (define case-cases cddr) (define (constructor? data-layouts x) (and (eqv? (ast-type x) 'var) (assoc x (flat-map cdr data-layouts)))) (define (all-cases data-layouts type) (let ([sums (assoc type data-layouts)]) (if sums (flat-map (lambda (sum) (let* ([sum-name (car sum)] [products (cdr sum)] [product-cases (map (lambda (y) (all-cases data-layouts y)) products)]) (if (null? product-cases) (list sum-name) ; singletons aren't enclosed in a list [(foo x) 42] vs [foo 42] (apply combinations (cons (list sum-name) product-cases))))) (cdr sums)) '(:binding)))) ; does a cover b (define (case-covers? data-layouts a b) (let ([a-binding? (and (eqv? (ast-type a) 'var) (not (constructor? data-layouts a)))]) (cond [(eqv? ':binding b) a-binding?] [a-binding? #t] ; a literal/singleton [(eqv? (ast-type b) 'var) (eqv? b a)] ; two different constructors [(not (eqv? (car a) (car b))) #f] ; two same constructors [else (all (map (lambda (p q) (case-covers? data-layouts p q)) (cdr a) (cdr b)))]))) (define (verify-cases data-layouts annotated-program) ;; (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))] [cases (map car (case-cases expr))] [case-covered? (lambda (x) (any (lambda (y) (case-covers? data-layouts y x)) cases))]) (unless (all (map case-covered? (all-cases data-layouts switch-type))) (error #f "not all cases covered")))] [else (ast-traverse (lambda (x) (verify-cases data-layouts x)) expr)]))) ; (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) '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)))) ; for use in normalized form (define lambda-arg caadr) ; for use elsewhere (define lambda-args cadr) (define lambda-body caddr) (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 (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) (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)) (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))