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))
67 (define (any p x) (fold-left
68 (lambda (acc y) (if acc #t (p y)))
74 (apply either (cdr fs)))))
78 (any inner (let-bindings x))
79 (any inner (let-body x)))]
82 ['lambda (either (p x)
83 (inner (lambda-body x)))]
84 ['if (either (p x) (any inner (cdr x)))]
86 (any inner (map cadr (case-cases x)))
87 (inner (case-switch x)))]
88 ['stack (either (p x) (inner (caddr x)))]
91 (define let-bindings cadr)
92 (define let-body cddr)
94 (define case-switch cadr)
95 (define case-cases cddr)
97 ;; (define (verify-cases data-layouts annotated-program)
99 ;; (define allowed-match-ast-types
100 ;; '((Int . (int-literal var))
101 ;; (Bool . (bool-literal var))
102 ;; (String . (string-literal var))))
104 ;; (define (check-pattern switch-type pat)
106 ;; (define (impossible-match)
107 ;; (error "Can't pattern match ~a with ~a" switch-type (ann-expr pat)))
109 ;; (if (assoc switch-type data-layouts)
111 ;; (let ([sums (cdr (assoc switch-type data-layouts))])
112 ;; (unless (eqv? (ast-type (ann-expr pat)) 'var) (impossible-match))
113 ;; (unless (assoc (car (ann-expr pat)) sums) (impossible-match))
117 ;; (unless (assoc switch-type allowed-match-ast-types)
118 ;; (error #f "Can't pattern match on ~a" switch-type))
120 ;; (let ([allowed (cdr (assoc switch-type allowed-match-ast-types))])
121 ;; (unless (assoc (ast-type (ann-expr pat)) allowed) (impossible-match)))))))
124 ;; (let ([expr (ann-expr annotated-program)])
125 ;; (case (ast-type expr)
127 ;; (let* ([switch-type (ann-type (case-switch expr))]
128 ;; [allowed (cdr (assoc switch-type allowed-match-ast-types))])
133 ; (let ([(foo a b) (foo 123 345)]) a)
136 ; (let ([a (foo~0 (foo 123 345)]
137 ; [b (foo~1 (foo 123 345)]) a)
138 (define (expand-pattern-matches program)
140 (define (let-pattern-match binding)
141 (let ([binding-name (car binding)]
142 [body (cadr binding)])
143 (if (eqv? (ast-type binding-name) 'var)
144 (list (list binding-name body))
146 (let* ([sum-name (car binding-name)]
147 [destructor (lambda (i) (dtor-name sum-name i))]
148 [products (cdr binding-name)]
150 [data-layouts (program-data-layouts program)]
152 [type (data-tor-type data-layouts sum-name)]
154 [sums (cdr (assoc type data-layouts))]
155 [sum (assoc sum-name sums)]
157 [expected-number (length (cdr sum))])
159 ; assert that we only do a let pattern match on an ADT with exactly one sum
160 (when (not (= 1 (length sums)))
161 (error #f (format "Cannot pattern match a ~a in a let since it has ~a possible constructors"
165 ; assert that there is the correct number of bindings
166 (when (not (= (length products)
168 (error #f (format "Got ~a bindings: expected ~a for ~a"
173 (flat-map (lambda (y i)
174 (let-pattern-match (list y `(,(destructor i) ,body))))
176 (range 0 (length products)))))))
179 ['let `(let ,(flat-map let-pattern-match (let-bindings x))
180 ,@(map go (let-body x)))]
181 [else (ast-traverse go x)]))
182 (program-map-exprs go program))
185 (and (list? x) (eq? (car x) 'lambda)))
187 (define (statement-type x)
190 (eqv? (car x) 'data)) 'data]
192 (eqv? (car x) 'define)) 'define]
196 ; (A ((foo (Int Bool))
198 (define (program-data-layouts program)
199 (map (lambda (x) (cons (car x) (cdr x))) ; convert to assoc list
200 (map cdr (filter (lambda (x) (eqv? (statement-type x) 'data))
203 (define (program-defines program)
204 (filter (lambda (x) (eqv? (statement-type x) 'defines))
207 (define (program-map-exprs f program)
209 (case (statement-type x)
214 (define (program-body program)
215 ; hack to have multi-expression bodies
217 ,@(filter (lambda (x) (eqv? (statement-type x) 'expr))
220 (define (data-tor-type data-layouts tor)
221 (let* ([tors (flat-map data-tors data-layouts)]
222 [info (cadr (assoc tor tors))])
225 ; a data tor is either a constructor or destructor for an ADT
226 ; data-tors returns constructors and destructors for a data-layout
227 ; (data A (foo Int Bool)
231 ; (foo . ((A foo constructor) . (abs Int (abs Bool A))))
232 ; (foo~0 . ((A foo 0 Int) . (abs A Int)))
233 ; (foo~1 . ((A foo 1 Bool) . (abs A Bool)))
234 ; (bar . ((A bar constructor) . (abs Bool A)))
235 ; (bar~0 . ((A bar 0 Bool) . (abs A Bool)))
236 ; ------+-------------------------------------
239 (define (data-tors data-layout)
240 (define (constructor-type t products)
241 (fold-right (lambda (x acc) `(abs ,x ,acc)) t products))
243 (define (destructor ctor-name prod-type part-type index)
244 (let* ([name (dtor-name ctor-name index)]
245 [info (list prod-type ctor-name index part-type)])
246 (cons name (cons info `(abs ,prod-type ,part-type)))))
248 (let ([type-name (car data-layout)]
249 [ctors (cdr data-layout)])
252 (let* ([ctor-name (car ctor)]
253 [products (cdr ctor)]
255 [maker (cons ctor-name (cons (list type-name ctor-name 'constructor) (constructor-type type-name products)))]
257 [dtors (map (lambda (t i) (destructor ctor-name type-name t i))
259 (range 0 (length products)))])
260 (cons maker (append dtors acc))))
264 ; creates a type environment for a given adt definition
265 (define (data-tors-type-env data-layout)
266 (map (lambda (x) (cons (car x) (cddr x))) (data-tors data-layout)))
268 (define (dtor-name ctor-name index)
270 (string-append (symbol->string ctor-name)
272 (number->string index))))
274 ; for use in normalized form
275 (define lambda-arg caadr)
277 (define lambda-args cadr)
278 (define lambda-body caddr)
280 (define (references prog)
289 (define (go bs orig-bs)
292 (let* [(bind (car bs))
295 (refs (filter ; only count a reference if its a binding
296 (lambda (x) (assoc x orig-bs))
297 (references (cdr bind))))
298 (edges (map (lambda (x) (cons vert x))
301 (rest (if (null? (cdr bs))
303 (go (cdr bs) orig-bs)))
304 (total-verts (cons vert (car rest)))
305 (total-edges (append edges (cdr rest)))]
306 (cons total-verts total-edges))))
309 (define (successors graph v)
313 (if (eqv? v (caar E))
314 (cons (cdar E) (go v (cdr E)))
318 ; takes in a graph (pair of vertices, edges)
319 ; returns a list of strongly connected components
321 ; ((x y w) . ((x . y) (x . w) (w . x))
331 ; this uses tarjan's algorithm, to get reverse
332 ; topological sorting for free
335 (let* ([indices (make-hash-table)]
336 [lowlinks (make-hash-table)]
337 [on-stack (make-hash-table)]
343 (get-hash-table indices v #f))
345 (get-hash-table lowlinks v #f))
351 (put-hash-table! indices v current)
352 (put-hash-table! lowlinks v current)
353 (set! current (+ current 1))
355 (put-hash-table! on-stack v #t)
359 (if (not (hashtable-contains? indices w))
360 ; successor w has not been visited, recurse
363 (put-hash-table! lowlinks
365 (min (lowlink v) (lowlink w))))
366 ; successor w has been visited
367 (when (get-hash-table on-stack w #f)
368 (put-hash-table! lowlinks v (min (lowlink v) (index w))))))
369 (successors graph v))
371 (when (= (index v) (lowlink v))
374 (let ([w (pop! stack)])
375 (put-hash-table! on-stack w #f)
378 (cons w (new-scc)))))])
379 (set! result (cons scc result))))))])
382 (when (not (hashtable-contains? indices v)) ; v.index == -1