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)))])
109 [(eqv? ':binding b) a-binding?]
111 ; a literal/singleton
112 [(eqv? (ast-type b) 'var) (eqv? b a)]
113 ; two different constructors
114 [(not (eqv? (car a) (car b))) #f]
115 ; two same constructors
117 (all (map (lambda (p q)
118 (case-covers? data-layouts p q))
119 (cdr a) (cdr b)))])))
121 (define (verify-cases data-layouts annotated-program)
123 ;; (define (check-pattern switch-type pat)
125 ;; (define (impossible-match)
126 ;; (error "Can't pattern match ~a with ~a" switch-type (ann-expr pat)))
128 ;; (if (assoc switch-type data-layouts)
130 ;; (let ([sums (cdr (assoc switch-type data-layouts))])
131 ;; (unless (eqv? (ast-type (ann-expr pat)) 'var) (impossible-match))
132 ;; (unless (assoc (car (ann-expr pat)) sums) (impossible-match))
136 ;; (unless (assoc switch-type allowed-match-ast-types)
137 ;; (error #f "Can't pattern match on ~a" switch-type))
139 ;; (let ([allowed (cdr (assoc switch-type allowed-match-ast-types))])
140 ;; (unless (assoc (ast-type (ann-expr pat)) allowed) (impossible-match)))))))
143 (let ([expr (ann-expr annotated-program)])
144 (case (ast-type expr)
146 (let* ([switch-type (ann-type (case-switch expr))]
147 [cases (map car (case-cases expr))]
149 (lambda (x) (any (lambda (y) (case-covers? data-layouts y x)) cases))])
150 (unless (all (map case-covered? (all-cases data-layouts switch-type)))
151 (error #f "not all cases covered")))]
152 [else (ast-traverse (lambda (x) (verify-cases data-layouts x)) expr)])))
155 ; (let ([(foo a b) (foo 123 345)]) a)
158 ; (let ([a (foo~0 (foo 123 345)]
159 ; [b (foo~1 (foo 123 345)]) a)
160 (define (expand-pattern-matches program)
162 (define (let-pattern-match binding)
163 (let ([binding-name (car binding)]
164 [body (cadr binding)])
165 (if (eqv? (ast-type binding-name) 'var)
166 (list (list binding-name body))
168 (let* ([sum-name (car binding-name)]
169 [destructor (lambda (i) (dtor-name sum-name i))]
170 [products (cdr binding-name)]
172 [data-layouts (program-data-layouts program)]
174 [type (data-tor-type data-layouts sum-name)]
176 [sums (cdr (assoc type data-layouts))]
177 [sum (assoc sum-name sums)]
179 [expected-number (length (cdr sum))])
181 ; assert that we only do a let pattern match on an ADT with exactly one sum
182 (when (not (= 1 (length sums)))
183 (error #f (format "Cannot pattern match a ~a in a let since it has ~a possible constructors"
187 ; assert that there is the correct number of bindings
188 (when (not (= (length products)
190 (error #f (format "Got ~a bindings: expected ~a for ~a"
195 (flat-map (lambda (y i)
196 (let-pattern-match (list y `(,(destructor i) ,body))))
198 (range 0 (length products)))))))
201 ['let `(let ,(flat-map let-pattern-match (let-bindings x))
202 ,@(map go (let-body x)))]
203 [else (ast-traverse go x)]))
204 (program-map-exprs go program))
207 (and (list? x) (eq? (car x) 'lambda)))
209 (define (statement-type x)
212 (eqv? (car x) 'data)) 'data]
214 (eqv? (car x) 'define)) 'define]
218 ; (A ((foo (Int Bool))
220 (define (program-data-layouts program)
221 (map (lambda (x) (cons (car x) (cdr x))) ; convert to assoc list
222 (map cdr (filter (lambda (x) (eqv? (statement-type x) 'data))
225 (define (program-defines program)
226 (filter (lambda (x) (eqv? (statement-type x) 'defines))
229 (define (program-map-exprs f program)
231 (case (statement-type x)
236 (define (program-body program)
237 ; hack to have multi-expression bodies
239 ,@(filter (lambda (x) (eqv? (statement-type x) 'expr))
242 (define (data-tor-type data-layouts tor)
243 (let* ([tors (flat-map data-tors data-layouts)]
244 [info (cadr (assoc tor tors))])
247 ; a data tor is either a constructor or destructor for an ADT
248 ; data-tors returns constructors and destructors for a data-layout
249 ; (data A (foo Int Bool)
253 ; (foo . ((A foo constructor) . (abs Int (abs Bool A))))
254 ; (foo~0 . ((A foo 0 Int) . (abs A Int)))
255 ; (foo~1 . ((A foo 1 Bool) . (abs A Bool)))
256 ; (bar . ((A bar constructor) . (abs Bool A)))
257 ; (bar~0 . ((A bar 0 Bool) . (abs A Bool)))
258 ; ------+-------------------------------------
261 (define (data-tors data-layout)
262 (define (constructor-type t products)
263 (fold-right (lambda (x acc) `(abs ,x ,acc)) t products))
265 (define (destructor ctor-name prod-type part-type index)
266 (let* ([name (dtor-name ctor-name index)]
267 [info (list prod-type ctor-name index part-type)])
268 (cons name (cons info `(abs ,prod-type ,part-type)))))
270 (let ([type-name (car data-layout)]
271 [ctors (cdr data-layout)])
274 (let* ([ctor-name (car ctor)]
275 [products (cdr ctor)]
277 [maker (cons ctor-name (cons (list type-name ctor-name 'constructor) (constructor-type type-name products)))]
279 [dtors (map (lambda (t i) (destructor ctor-name type-name t i))
281 (range 0 (length products)))])
282 (cons maker (append dtors acc))))
286 ; creates a type environment for a given adt definition
287 (define (data-tors-type-env data-layout)
288 (map (lambda (x) (cons (car x) (cddr x))) (data-tors data-layout)))
290 (define (dtor-name ctor-name index)
292 (string-append (symbol->string ctor-name)
294 (number->string index))))
296 ; for use in normalized form
297 (define lambda-arg caadr)
299 (define lambda-args cadr)
300 (define lambda-body caddr)
302 (define (references prog)
311 (define (go bs orig-bs)
314 (let* [(bind (car bs))
317 (refs (filter ; only count a reference if its a binding
318 (lambda (x) (assoc x orig-bs))
319 (references (cdr bind))))
320 (edges (map (lambda (x) (cons vert x))
323 (rest (if (null? (cdr bs))
325 (go (cdr bs) orig-bs)))
326 (total-verts (cons vert (car rest)))
327 (total-edges (append edges (cdr rest)))]
328 (cons total-verts total-edges))))
331 (define (successors graph v)
335 (if (eqv? v (caar E))
336 (cons (cdar E) (go v (cdr E)))
340 ; takes in a graph (pair of vertices, edges)
341 ; returns a list of strongly connected components
343 ; ((x y w) . ((x . y) (x . w) (w . x))
353 ; this uses tarjan's algorithm, to get reverse
354 ; topological sorting for free
357 (let* ([indices (make-hash-table)]
358 [lowlinks (make-hash-table)]
359 [on-stack (make-hash-table)]
365 (get-hash-table indices v #f))
367 (get-hash-table lowlinks v #f))
373 (put-hash-table! indices v current)
374 (put-hash-table! lowlinks v current)
375 (set! current (+ current 1))
377 (put-hash-table! on-stack v #t)
381 (if (not (hashtable-contains? indices w))
382 ; successor w has not been visited, recurse
385 (put-hash-table! lowlinks
387 (min (lowlink v) (lowlink w))))
388 ; successor w has been visited
389 (when (get-hash-table on-stack w #f)
390 (put-hash-table! lowlinks v (min (lowlink v) (index w))))))
391 (successors graph v))
393 (when (= (index v) (lowlink v))
396 (let ([w (pop! stack)])
397 (put-hash-table! on-stack w #f)
400 (cons w (new-scc)))))])
401 (set! result (cons scc result))))))])
404 (when (not (hashtable-contains? indices v)) ; v.index == -1