21 ('closure 'closure) ; only available in codegen
22 ('static-string 'static-string) ; only available in codegen
23 ('stack 'stack) ; only available in codegen (tag that value is passed via stack)
25 ((builtin? x) 'builtin)
27 ((integer? x) 'int-literal)
28 ((boolean? x) 'bool-literal)
29 ((string? x) 'string-literal)))
31 (define (ast-traverse f x)
33 ('let `(let ,(map (lambda (x) (list (car x) (f (cadr x))))
35 ,@(map f (let-body x))))
37 ('lambda `(lambda ,(lambda-args x) ,(f (lambda-body x))))
38 ('if `(if ,@(map f (cdr x))))
39 ('case `(case ,(f (case-switch x))
41 (list (car x) (f (cadr x))))
43 ('stack `(stack ,(cadr x) ,(f (caddr x))))
46 (define (ast-collect f x)
47 (define (inner y) (ast-collect f y))
50 (flat-map inner (let-bindings x))
51 (flat-map inner (let-body x)))]
54 ['lambda (append (f x)
55 (inner (lambda-body x)))]
57 (flat-map inner (cdr x)))]
59 (inner (case-switch x))
60 (flat-map inner (map cadr (case-cases x))))]
65 (define (ast-find p x)
66 (define (inner y) (ast-find p y))
70 (any inner (let-bindings x))
71 (any inner (let-body x)))]
75 (inner (lambda-body x)))]
76 ['if (or (p x) (any inner (cdr x)))]
78 (any inner (map cadr (case-cases x)))
79 (inner (case-switch x)))]
80 ['stack (or (p x) (inner (caddr x)))]
83 (define let-bindings cadr)
84 (define let-body cddr)
86 (define case-switch cadr)
87 (define case-cases cddr)
89 (define (constructor? data-layouts x)
90 (and (eqv? (ast-type x) 'var)
91 (assoc x (flat-map cdr data-layouts))))
93 (define (all-cases data-layouts type)
94 (let ([sums (assoc type data-layouts)])
96 (flat-map (lambda (sum)
97 (let* ([sum-name (car sum)]
99 [product-cases (map (lambda (y) (all-cases data-layouts y)) products)])
100 (if (null? product-cases)
101 (list sum-name) ; singletons aren't enclosed in a list [(foo x) 42] vs [foo 42]
102 (apply combinations (cons (list sum-name) product-cases)))))
107 (define (case-covers? data-layouts a b)
108 (let ([a-binding? (and (eqv? (ast-type a) 'var) (not (constructor? data-layouts a)))])
109 (if (eqv? ':binding b)
113 (if (eqv? (ast-type b) 'var)
115 (all (map (lambda (p q)
116 (case-covers? data-layouts p q))
117 (cdr a) (cdr b))))))))
119 (define (verify-cases data-layouts annotated-program)
121 ;; (define (check-pattern switch-type pat)
123 ;; (define (impossible-match)
124 ;; (error "Can't pattern match ~a with ~a" switch-type (ann-expr pat)))
126 ;; (if (assoc switch-type data-layouts)
128 ;; (let ([sums (cdr (assoc switch-type data-layouts))])
129 ;; (unless (eqv? (ast-type (ann-expr pat)) 'var) (impossible-match))
130 ;; (unless (assoc (car (ann-expr pat)) sums) (impossible-match))
134 ;; (unless (assoc switch-type allowed-match-ast-types)
135 ;; (error #f "Can't pattern match on ~a" switch-type))
137 ;; (let ([allowed (cdr (assoc switch-type allowed-match-ast-types))])
138 ;; (unless (assoc (ast-type (ann-expr pat)) allowed) (impossible-match)))))))
141 (let ([expr (ann-expr annotated-program)])
142 (case (ast-type expr)
144 (let* ([switch-type (ann-type (case-switch expr))]
145 [cases (map car (case-cases expr))]
147 (lambda (x) (any (lambda (y) (case-covers? data-layouts y x)) cases))])
148 (unless (all (map case-covered? (all-cases data-layouts switch-type)))
149 (error #f "not all cases covered")))]
150 [else (ast-traverse (lambda (x) (verify-cases data-layouts x)) expr)])))
153 ; (let ([(foo a b) (foo 123 345)]) a)
156 ; (let ([a (foo~0 (foo 123 345)]
157 ; [b (foo~1 (foo 123 345)]) a)
158 (define (expand-pattern-matches program)
160 (define (let-pattern-match binding)
161 (let ([binding-name (car binding)]
162 [body (cadr binding)])
163 (if (eqv? (ast-type binding-name) 'var)
164 (list (list binding-name body))
166 (let* ([sum-name (car binding-name)]
167 [destructor (lambda (i) (dtor-name sum-name i))]
168 [products (cdr binding-name)]
170 [data-layouts (program-data-layouts program)]
172 [type (data-tor-type data-layouts sum-name)]
174 [sums (cdr (assoc type data-layouts))]
175 [sum (assoc sum-name sums)]
177 [expected-number (length (cdr sum))])
179 ; assert that we only do a let pattern match on an ADT with exactly one sum
180 (when (not (= 1 (length sums)))
181 (error #f (format "Cannot pattern match a ~a in a let since it has ~a possible constructors"
185 ; assert that there is the correct number of bindings
186 (when (not (= (length products)
188 (error #f (format "Got ~a bindings: expected ~a for ~a"
193 (flat-map (lambda (y i)
194 (let-pattern-match (list y `(,(destructor i) ,body))))
196 (range 0 (length products)))))))
199 ['let `(let ,(flat-map let-pattern-match (let-bindings x))
200 ,@(map go (let-body x)))]
201 [else (ast-traverse go x)]))
202 (program-map-exprs go program))
205 (and (list? x) (eq? (car x) 'lambda)))
207 (define (statement-type x)
210 (eqv? (car x) 'data)) 'data]
212 (eqv? (car x) 'define)) 'define]
216 ; (A ((foo (Int Bool))
218 (define (program-data-layouts program)
219 (map (lambda (x) (cons (car x) (cdr x))) ; convert to assoc list
220 (map cdr (filter (lambda (x) (eqv? (statement-type x) 'data))
223 (define (program-defines program)
224 (filter (lambda (x) (eqv? (statement-type x) 'defines))
227 (define (program-map-exprs f program)
229 (case (statement-type x)
234 (define (program-body program)
235 ; hack to have multi-expression bodies
237 ,@(filter (lambda (x) (eqv? (statement-type x) 'expr))
240 (define (data-tor-type data-layouts tor)
241 (let* ([tors (flat-map data-tors data-layouts)]
242 [info (cadr (assoc tor tors))])
245 ; a data tor is either a constructor or destructor for an ADT
246 ; data-tors returns constructors and destructors for a data-layout
247 ; (data A (foo Int Bool)
251 ; (foo . ((A foo constructor) . (abs Int (abs Bool A))))
252 ; (foo~0 . ((A foo 0 Int) . (abs A Int)))
253 ; (foo~1 . ((A foo 1 Bool) . (abs A Bool)))
254 ; (bar . ((A bar constructor) . (abs Bool A)))
255 ; (bar~0 . ((A bar 0 Bool) . (abs A Bool)))
256 ; ------+-------------------------------------
259 (define (data-tors data-layout)
260 (define (constructor-type t products)
261 (fold-right (lambda (x acc) `(abs ,x ,acc)) t products))
263 (define (destructor ctor-name prod-type part-type index)
264 (let* ([name (dtor-name ctor-name index)]
265 [info (list prod-type ctor-name index part-type)])
266 (cons name (cons info `(abs ,prod-type ,part-type)))))
268 (let ([type-name (car data-layout)]
269 [ctors (cdr data-layout)])
272 (let* ([ctor-name (car ctor)]
273 [products (cdr ctor)]
275 [maker (cons ctor-name (cons (list type-name ctor-name 'constructor) (constructor-type type-name products)))]
277 [dtors (map (lambda (t i) (destructor ctor-name type-name t i))
279 (range 0 (length products)))])
280 (cons maker (append dtors acc))))
284 ; creates a type environment for a given adt definition
285 (define (data-tors-type-env data-layout)
286 (map (lambda (x) (cons (car x) (cddr x))) (data-tors data-layout)))
288 (define (dtor-name ctor-name index)
290 (string-append (symbol->string ctor-name)
292 (number->string index))))
294 ; for use in normalized form
295 (define lambda-arg caadr)
297 (define lambda-args cadr)
298 (define lambda-body caddr)
300 (define (references prog)
309 (define (go bs orig-bs)
312 (let* [(bind (car bs))
315 (refs (filter ; only count a reference if its a binding
316 (lambda (x) (assoc x orig-bs))
317 (references (cdr bind))))
318 (edges (map (lambda (x) (cons vert x))
321 (rest (if (null? (cdr bs))
323 (go (cdr bs) orig-bs)))
324 (total-verts (cons vert (car rest)))
325 (total-edges (append edges (cdr rest)))]
326 (cons total-verts total-edges))))
329 (define (successors graph v)
333 (if (eqv? v (caar E))
334 (cons (cdar E) (go v (cdr E)))
338 ; takes in a graph (pair of vertices, edges)
339 ; returns a list of strongly connected components
341 ; ((x y w) . ((x . y) (x . w) (w . x))
351 ; this uses tarjan's algorithm, to get reverse
352 ; topological sorting for free
355 (let* ([indices (make-hash-table)]
356 [lowlinks (make-hash-table)]
357 [on-stack (make-hash-table)]
363 (get-hash-table indices v #f))
365 (get-hash-table lowlinks v #f))
371 (put-hash-table! indices v current)
372 (put-hash-table! lowlinks v current)
373 (set! current (+ current 1))
375 (put-hash-table! on-stack v #t)
379 (if (not (hashtable-contains? indices w))
380 ; successor w has not been visited, recurse
383 (put-hash-table! lowlinks
385 (min (lowlink v) (lowlink w))))
386 ; successor w has been visited
387 (when (get-hash-table on-stack w #f)
388 (put-hash-table! lowlinks v (min (lowlink v) (index w))))))
389 (successors graph v))
391 (when (= (index v) (lowlink v))
394 (let ([w (pop! stack)])
395 (put-hash-table! on-stack w #f)
398 (cons w (new-scc)))))])
399 (set! result (cons scc result))))))])
402 (when (not (hashtable-contains? indices v)) ; v.index == -1