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)))]
85 ['stack (either (p x) (inner (caddr x)))]
88 (define let-bindings cadr)
89 (define let-body cddr)
91 (define case-switch cadr)
92 (define case-cases cddr)
94 ;; (define (verify-cases data-layouts annotated-program)
96 ;; (define allowed-match-ast-types
97 ;; '((Int . (int-literal var))
98 ;; (Bool . (bool-literal var))
99 ;; (String . (string-literal var))))
101 ;; (define (check-pattern switch-type pat)
103 ;; (define (impossible-match)
104 ;; (error "Can't pattern match ~a with ~a" switch-type (ann-expr pat)))
106 ;; (if (assoc switch-type data-layouts)
108 ;; (let ([sums (cdr (assoc switch-type data-layouts))])
109 ;; (unless (eqv? (ast-type (ann-expr pat)) 'var) (impossible-match))
110 ;; (unless (assoc (car (ann-expr pat)) sums) (impossible-match))
114 ;; (unless (assoc switch-type allowed-match-ast-types)
115 ;; (error #f "Can't pattern match on ~a" switch-type))
117 ;; (let ([allowed (cdr (assoc switch-type allowed-match-ast-types))])
118 ;; (unless (assoc (ast-type (ann-expr pat)) allowed) (impossible-match)))))))
121 ;; (let ([expr (ann-expr annotated-program)])
122 ;; (case (ast-type expr)
124 ;; (let* ([switch-type (ann-type (case-switch expr))]
125 ;; [allowed (cdr (assoc switch-type allowed-match-ast-types))])
130 ; (let ([(foo a b) (foo 123 345)]) a)
133 ; (let ([a (foo~0 (foo 123 345)]
134 ; [b (foo~1 (foo 123 345)]) a)
135 (define (expand-pattern-matches program)
137 (define (let-pattern-match binding)
138 (let ([binding-name (car binding)]
139 [body (cadr binding)])
140 (if (eqv? (ast-type binding-name) 'var)
141 (list (list binding-name body))
143 (let* ([sum-name (car binding-name)]
144 [destructor (lambda (i) (dtor-name sum-name i))]
145 [products (cdr binding-name)]
147 [data-layouts (program-data-layouts program)]
149 [type (data-tor-type data-layouts sum-name)]
151 [sums (cdr (assoc type data-layouts))]
152 [sum (assoc sum-name sums)]
154 [expected-number (length (cdr sum))])
156 ; assert that we only do a let pattern match on an ADT with exactly one sum
157 (when (not (= 1 (length sums)))
158 (error #f (format "Cannot pattern match a ~a in a let since it has ~a possible constructors"
162 ; assert that there is the correct number of bindings
163 (when (not (= (length products)
165 (error #f (format "Got ~a bindings: expected ~a for ~a"
170 (flat-map (lambda (y i)
171 (let-pattern-match (list y `(,(destructor i) ,body))))
173 (range 0 (length products)))))))
176 ['let `(let ,(flat-map let-pattern-match (let-bindings x))
177 ,@(map go (let-body x)))]
178 [else (ast-traverse go x)]))
179 (program-map-exprs go program))
182 (and (list? x) (eq? (car x) 'lambda)))
184 (define (statement-type x)
187 (eqv? (car x) 'data)) 'data]
189 (eqv? (car x) 'define)) 'define]
193 ; (A ((foo (Int Bool))
195 (define (program-data-layouts program)
196 (map (lambda (x) (cons (car x) (cdr x))) ; convert to assoc list
197 (map cdr (filter (lambda (x) (eqv? (statement-type x) 'data))
200 (define (program-defines program)
201 (filter (lambda (x) (eqv? (statement-type x) 'defines))
204 (define (program-map-exprs f program)
206 (case (statement-type x)
211 (define (program-body program)
212 ; hack to have multi-expression bodies
214 ,@(filter (lambda (x) (eqv? (statement-type x) 'expr))
217 (define (data-tor-type data-layouts tor)
218 (let* ([tors (flat-map data-tors data-layouts)]
219 [info (cadr (assoc tor tors))])
222 ; a data tor is either a constructor or destructor for an ADT
223 ; data-tors returns constructors and destructors for a data-layout
224 ; (data A (foo Int Bool)
228 ; (foo . ((A foo constructor) . (abs Int (abs Bool A))))
229 ; (foo~0 . ((A foo 0 Int) . (abs A Int)))
230 ; (foo~1 . ((A foo 1 Bool) . (abs A Bool)))
231 ; (bar . ((A bar constructor) . (abs Bool A)))
232 ; (bar~0 . ((A bar 0 Bool) . (abs A Bool)))
233 ; ------+-------------------------------------
236 (define (data-tors data-layout)
237 (define (constructor-type t products)
238 (fold-right (lambda (x acc) `(abs ,x ,acc)) t products))
240 (define (destructor ctor-name prod-type part-type index)
241 (let* ([name (dtor-name ctor-name index)]
242 [info (list prod-type ctor-name index part-type)])
243 (cons name (cons info `(abs ,prod-type ,part-type)))))
245 (let ([type-name (car data-layout)]
246 [ctors (cdr data-layout)])
249 (let* ([ctor-name (car ctor)]
250 [products (cdr ctor)]
252 [maker (cons ctor-name (cons (list type-name ctor-name 'constructor) (constructor-type type-name products)))]
254 [dtors (map (lambda (t i) (destructor ctor-name type-name t i))
256 (range 0 (length products)))])
257 (cons maker (append dtors acc))))
261 ; creates a type environment for a given adt definition
262 (define (data-tors-type-env data-layout)
263 (map (lambda (x) (cons (car x) (cddr x))) (data-tors data-layout)))
265 (define (dtor-name ctor-name index)
267 (string-append (symbol->string ctor-name)
269 (number->string index))))
271 ; for use in normalized form
272 (define lambda-arg caadr)
274 (define lambda-args cadr)
275 (define lambda-body caddr)
277 (define (references prog)
286 (define (go bs orig-bs)
289 (let* [(bind (car bs))
292 (refs (filter ; only count a reference if its a binding
293 (lambda (x) (assoc x orig-bs))
294 (references (cdr bind))))
295 (edges (map (lambda (x) (cons vert x))
298 (rest (if (null? (cdr bs))
300 (go (cdr bs) orig-bs)))
301 (total-verts (cons vert (car rest)))
302 (total-edges (append edges (cdr rest)))]
303 (cons total-verts total-edges))))
306 (define (successors graph v)
310 (if (eqv? v (caar E))
311 (cons (cdar E) (go v (cdr E)))
315 ; takes in a graph (pair of vertices, edges)
316 ; returns a list of strongly connected components
318 ; ((x y w) . ((x . y) (x . w) (w . x))
328 ; this uses tarjan's algorithm, to get reverse
329 ; topological sorting for free
332 (let* ([indices (make-hash-table)]
333 [lowlinks (make-hash-table)]
334 [on-stack (make-hash-table)]
340 (get-hash-table indices v #f))
342 (get-hash-table lowlinks v #f))
348 (put-hash-table! indices v current)
349 (put-hash-table! lowlinks v current)
350 (set! current (+ current 1))
352 (put-hash-table! on-stack v #t)
356 (if (not (hashtable-contains? indices w))
357 ; successor w has not been visited, recurse
360 (put-hash-table! lowlinks
362 (min (lowlink v) (lowlink w))))
363 ; successor w has been visited
364 (when (get-hash-table on-stack w #f)
365 (put-hash-table! lowlinks v (min (lowlink v) (index w))))))
366 (successors graph v))
368 (when (= (index v) (lowlink v))
371 (let ([w (pop! stack)])
372 (put-hash-table! on-stack w #f)
375 (cons w (new-scc)))))])
376 (set! result (cons scc result))))))])
379 (when (not (hashtable-contains? indices v)) ; v.index == -1