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 ((string? x) 'string-literal)))
30 (define (ast-traverse f x)
32 ('let `(let ,(map (lambda (x) (list (car x) (f (cadr x))))
34 ,@(map f (let-body x))))
36 ('lambda `(lambda ,(lambda-args x) ,(f (lambda-body x))))
37 ('if `(if ,@(map f (cdr x))))
38 ('case `(case ,(f (case-switch x))
40 (list (car x) (f (cadr x))))
42 ('stack `(stack ,(cadr x) ,(f (caddr x))))
45 (define (ast-collect f x)
46 (define (inner y) (ast-collect f y))
49 (flat-map inner (let-bindings x))
50 (flat-map inner (let-body x)))]
53 ['lambda (append (f x)
54 (inner (lambda-body x)))]
56 (flat-map inner (cdr x)))]
58 (inner (case-switch x))
59 (flat-map inner (map cadr (case-cases x))))]
64 (define (ast-find p x)
65 (define (inner y) (ast-find p y))
69 (any inner (let-bindings x))
70 (any inner (let-body x)))]
74 (inner (lambda-body x)))]
75 ['if (or (p x) (any inner (cdr x)))]
77 (any inner (map cadr (case-cases x)))
78 (inner (case-switch x)))]
79 ['stack (or (p x) (inner (caddr x)))]
82 (define let-bindings cadr)
83 (define let-body cddr)
85 (define case-switch cadr)
86 (define case-cases cddr)
88 (define (constructor? data-layouts x)
89 (and (eqv? (ast-type x) 'var)
90 (assoc x (flat-map cdr data-layouts))))
92 (define (all-cases data-layouts type)
93 (let ([sums (assoc type data-layouts)])
95 (flat-map (lambda (sum)
96 (let* ([sum-name (car sum)]
98 [product-cases (map (lambda (y) (all-cases data-layouts y)) products)])
99 (if (null? product-cases)
100 (list sum-name) ; singletons aren't enclosed in a list [(foo x) 42] vs [foo 42]
101 (apply combinations (cons (list sum-name) product-cases)))))
106 (define (case-covers? data-layouts a b)
107 (let ([a-binding? (and (eqv? (ast-type a) 'var) (not (constructor? data-layouts a)))])
108 (if (eqv? ':binding b)
112 (if (eqv? (ast-type b) 'var)
114 (all (map (lambda (p q)
115 (case-covers? data-layouts p q))
116 (cdr a) (cdr b))))))))
118 (define (verify-cases data-layouts annotated-program)
120 ;; (define (check-pattern switch-type pat)
122 ;; (define (impossible-match)
123 ;; (error "Can't pattern match ~a with ~a" switch-type (ann-expr pat)))
125 ;; (if (assoc switch-type data-layouts)
127 ;; (let ([sums (cdr (assoc switch-type data-layouts))])
128 ;; (unless (eqv? (ast-type (ann-expr pat)) 'var) (impossible-match))
129 ;; (unless (assoc (car (ann-expr pat)) sums) (impossible-match))
133 ;; (unless (assoc switch-type allowed-match-ast-types)
134 ;; (error #f "Can't pattern match on ~a" switch-type))
136 ;; (let ([allowed (cdr (assoc switch-type allowed-match-ast-types))])
137 ;; (unless (assoc (ast-type (ann-expr pat)) allowed) (impossible-match)))))))
140 (let ([expr (ann-expr annotated-program)])
141 (case (ast-type expr)
143 (let* ([switch-type (ann-type (case-switch expr))]
144 [cases (map car (case-cases expr))]
146 (lambda (x) (any (lambda (y) (case-covers? data-layouts y x)) cases))])
147 (unless (all (map case-covered? (all-cases data-layouts switch-type)))
148 (error #f "not all cases covered")))]
149 [else (ast-traverse (lambda (x) (verify-cases data-layouts x)) expr)])))
152 ; (let ([(foo a b) (foo 123 345)]) a)
155 ; (let ([a (foo~0 (foo 123 345)]
156 ; [b (foo~1 (foo 123 345)]) a)
157 (define (expand-pattern-matches program)
159 (define (let-pattern-match binding)
160 (let ([binding-name (car binding)]
161 [body (cadr binding)])
162 (if (eqv? (ast-type binding-name) 'var)
163 (list (list binding-name body))
165 (let* ([sum-name (car binding-name)]
166 [destructor (lambda (i) (dtor-name sum-name i))]
167 [products (cdr binding-name)]
169 [data-layouts (program-data-layouts program)]
171 [type (data-tor-type data-layouts sum-name)]
173 [sums (cdr (assoc type data-layouts))]
174 [sum (assoc sum-name sums)]
176 [expected-number (length (cdr sum))])
178 ; assert that we only do a let pattern match on an ADT with exactly one sum
179 (when (not (= 1 (length sums)))
180 (error #f (format "Cannot pattern match a ~a in a let since it has ~a possible constructors"
184 ; assert that there is the correct number of bindings
185 (when (not (= (length products)
187 (error #f (format "Got ~a bindings: expected ~a for ~a"
192 (flat-map (lambda (y i)
193 (let-pattern-match (list y `(,(destructor i) ,body))))
195 (range 0 (length products)))))))
198 ['let `(let ,(flat-map let-pattern-match (let-bindings x))
199 ,@(map go (let-body x)))]
200 [else (ast-traverse go x)]))
201 (program-map-exprs go program))
204 (and (list? x) (eq? (car x) 'lambda)))
206 (define (statement-type x)
209 (eqv? (car x) 'data)) 'data]
211 (eqv? (car x) 'define)) 'define]
215 ; (A ((foo (Int Bool))
217 (define (program-data-layouts program)
218 (map (lambda (x) (cons (car x) (cdr x))) ; convert to assoc list
219 (map cdr (filter (lambda (x) (eqv? (statement-type x) 'data))
222 (define (program-defines program)
223 (filter (lambda (x) (eqv? (statement-type x) 'defines))
226 (define (program-map-exprs f program)
228 (case (statement-type x)
233 (define (program-body program)
234 ; hack to have multi-expression bodies
236 ,@(filter (lambda (x) (eqv? (statement-type x) 'expr))
239 (define (data-tor-type data-layouts tor)
240 (let* ([tors (flat-map data-tors data-layouts)]
241 [info (cadr (assoc tor tors))])
244 ; a data tor is either a constructor or destructor for an ADT
245 ; data-tors returns constructors and destructors for a data-layout
246 ; (data A (foo Int Bool)
250 ; (foo . ((A foo constructor) . (abs Int (abs Bool A))))
251 ; (foo~0 . ((A foo 0 Int) . (abs A Int)))
252 ; (foo~1 . ((A foo 1 Bool) . (abs A Bool)))
253 ; (bar . ((A bar constructor) . (abs Bool A)))
254 ; (bar~0 . ((A bar 0 Bool) . (abs A Bool)))
255 ; ------+-------------------------------------
258 (define (data-tors data-layout)
259 (define (constructor-type t products)
260 (fold-right (lambda (x acc) `(abs ,x ,acc)) t products))
262 (define (destructor ctor-name prod-type part-type index)
263 (let* ([name (dtor-name ctor-name index)]
264 [info (list prod-type ctor-name index part-type)])
265 (cons name (cons info `(abs ,prod-type ,part-type)))))
267 (let ([type-name (car data-layout)]
268 [ctors (cdr data-layout)])
271 (let* ([ctor-name (car ctor)]
272 [products (cdr ctor)]
274 [maker (cons ctor-name (cons (list type-name ctor-name 'constructor) (constructor-type type-name products)))]
276 [dtors (map (lambda (t i) (destructor ctor-name type-name t i))
278 (range 0 (length products)))])
279 (cons maker (append dtors acc))))
283 ; creates a type environment for a given adt definition
284 (define (data-tors-type-env data-layout)
285 (map (lambda (x) (cons (car x) (cddr x))) (data-tors data-layout)))
287 (define (dtor-name ctor-name index)
289 (string-append (symbol->string ctor-name)
291 (number->string index))))
293 ; for use in normalized form
294 (define lambda-arg caadr)
296 (define lambda-args cadr)
297 (define lambda-body caddr)
299 (define (references prog)
308 (define (go bs orig-bs)
311 (let* [(bind (car bs))
314 (refs (filter ; only count a reference if its a binding
315 (lambda (x) (assoc x orig-bs))
316 (references (cdr bind))))
317 (edges (map (lambda (x) (cons vert x))
320 (rest (if (null? (cdr bs))
322 (go (cdr bs) orig-bs)))
323 (total-verts (cons vert (car rest)))
324 (total-edges (append edges (cdr rest)))]
325 (cons total-verts total-edges))))
328 (define (successors graph v)
332 (if (eqv? v (caar E))
333 (cons (cdar E) (go v (cdr E)))
337 ; takes in a graph (pair of vertices, edges)
338 ; returns a list of strongly connected components
340 ; ((x y w) . ((x . y) (x . w) (w . x))
350 ; this uses tarjan's algorithm, to get reverse
351 ; topological sorting for free
354 (let* ([indices (make-hash-table)]
355 [lowlinks (make-hash-table)]
356 [on-stack (make-hash-table)]
362 (get-hash-table indices v #f))
364 (get-hash-table lowlinks v #f))
370 (put-hash-table! indices v current)
371 (put-hash-table! lowlinks v current)
372 (set! current (+ current 1))
374 (put-hash-table! on-stack v #t)
378 (if (not (hashtable-contains? indices w))
379 ; successor w has not been visited, recurse
382 (put-hash-table! lowlinks
384 (min (lowlink v) (lowlink w))))
385 ; successor w has been visited
386 (when (get-hash-table on-stack w #f)
387 (put-hash-table! lowlinks v (min (lowlink v) (index w))))))
388 (successors graph v))
390 (when (= (index v) (lowlink v))
393 (let ([w (pop! stack)])
394 (put-hash-table! on-stack w #f)
397 (cons w (new-scc)))))])
398 (set! result (cons scc result))))))])
401 (when (not (hashtable-contains? indices v)) ; v.index == -1