18 ('closure 'closure) ; only available in codegen
19 ('static-string 'static-string) ; only available in codegen
20 ('stack 'stack) ; only available in codegen (tag that value is passed via stack)
22 ((builtin? x) 'builtin)
24 ((integer? x) 'int-literal)
25 ((boolean? x) 'bool-literal)
26 ((string? x) 'string-literal)))
28 (define (ast-traverse f x)
30 ('let `(let ,(map (lambda (x) (list (car x) (f (cadr x))))
32 ,@(map f (let-body x))))
34 ('lambda `(lambda ,(lambda-args x) ,(f (lambda-body x))))
35 ('if `(if ,@(map f (cdr x))))
36 ('stack `(stack ,(cadr x) ,(map f (caddr x))))
39 (define (ast-collect f x)
40 (define (inner y) (ast-collect f y))
43 (flat-map inner (let-bindings x))
44 (flat-map inner (let-body x)))]
47 ['lambda (append (f x)
48 (inner (lambda-body x)))]
50 (flat-map inner (cdr x)))]
55 (define (ast-find p x)
56 (define (inner y) (ast-find p y))
57 (define (any p x) (fold-left
58 (lambda (acc y) (if acc #t (p y)))
64 (apply either (cdr fs)))))
68 (any inner (let-bindings x))
69 (any inner (let-body x)))]
72 ['lambda (either (p x)
73 (inner (lambda-body x)))]
74 ['if (either (p x) (any inner (cdr x)))]
75 ['stack (either (p x) (inner (caddr x)))]
78 (define let-bindings cadr)
79 (define let-body cddr)
81 ; (let ([(foo a b) (foo 123 345)]) a)
84 ; (let ([a (foo~0 (foo 123 345)]
85 ; [b (foo~1 (foo 123 345)]) a)
86 (define (expand-pattern-matches program)
88 (define (pattern-match binding)
89 (let ([binding-name (car binding)]
90 [body (cadr binding)])
91 (if (eqv? (ast-type binding-name) 'var)
92 (list (list binding-name body))
94 (let* ([sum-name (car binding-name)]
95 [destructor (lambda (i) (dtor-name sum-name i))]
96 [products (cdr binding-name)]
98 [data-layouts (program-data-layouts program)]
100 [type (data-tor-type data-layouts sum-name)]
102 [sums (cdr (assoc type data-layouts))]
103 [sum (assoc sum-name sums)]
105 [expected-number (length (cdr sum))])
107 ; assert that we only do a let pattern match on an ADT with exactly one sum
108 (when (not (= 1 (length sums)))
109 (error #f (format "Cannot pattern match a ~a in a let since it has ~a possible constructors"
113 ; assert that there is the correct number of bindings
114 (when (not (= (length products)
116 (error #f (format "Got ~a bindings: expected ~a for ~a"
121 (flat-map (lambda (y i)
122 (pattern-match (list y `(,(destructor i) ,body))))
124 (range 0 (length products)))))))
126 ['let `(let ,(flat-map pattern-match (let-bindings x))
127 ,@(map go (let-body x)))]
128 [else (ast-traverse go x)]))
129 (program-map-exprs go program))
132 (and (list? x) (eq? (car x) 'lambda)))
134 (define (statement-type x)
137 (eqv? (car x) 'data)) 'data]
139 (eqv? (car x) 'define)) 'define]
143 ; (A ((foo (Int Bool))
145 (define (program-data-layouts program)
146 (map (lambda (x) (cons (car x) (cdr x))) ; convert to assoc list
147 (map cdr (filter (lambda (x) (eqv? (statement-type x) 'data))
150 (define (program-defines program)
151 (filter (lambda (x) (eqv? (statement-type x) 'defines))
154 (define (program-map-exprs f program)
156 (case (statement-type x)
161 (define (program-body program)
162 ; hack to have multi-expression bodies
164 ,@(filter (lambda (x) (eqv? (statement-type x) 'expr))
167 (define (data-tor-type data-layouts tor)
168 (let* ([tors (flat-map data-tors data-layouts)]
169 [info (cadr (assoc tor tors))])
172 ; a data tor is either a constructor or destructor for an ADT
173 ; data-tors returns constructors and destructors for a data-layout
174 ; (data A (foo Int Bool)
178 ; (foo . ((A foo constructor) . (abs Int (abs Bool A))))
179 ; (foo~0 . ((A foo 0) . (abs A Int)))
180 ; (foo~1 . ((A foo 1) . (abs A Bool)))
181 ; (bar . ((A bar constructor) . (abs Bool A)))
182 ; (bar~0 . ((A bar 0) . (abs A Bool)))
183 ; ------+-------------------------------------
186 (define (data-tors data-layout)
187 (define (constructor-type t products)
188 (fold-right (lambda (x acc) `(abs ,x ,acc)) t products))
190 (define (destructor ctor-name prod-type part-type index)
191 (let ([name (dtor-name ctor-name index)])
192 (cons name (cons (list prod-type ctor-name index) `(abs ,prod-type ,part-type)))))
194 (let ([type-name (car data-layout)]
195 [ctors (cdr data-layout)])
198 (let* ([ctor-name (car ctor)]
199 [products (cdr ctor)]
201 [maker (cons ctor-name (cons (list type-name ctor-name 'constructor) (constructor-type type-name products)))]
203 [dtors (map (lambda (t i) (destructor ctor-name type-name t i))
205 (range 0 (length products)))])
206 (cons maker (append dtors acc))))
210 ; creates a type environment for a given adt definition
211 (define (data-tors-type-env data-layout)
212 (map (lambda (x) (cons (car x) (cddr x))) (data-tors data-layout)))
214 (define (dtor-name ctor-name index)
216 (string-append (symbol->string ctor-name)
218 (number->string index))))
220 ; for use in normalized form
221 (define lambda-arg caadr)
223 (define lambda-args cadr)
224 (define lambda-body caddr)
226 (define (references prog)
235 (define (go bs orig-bs)
238 (let* [(bind (car bs))
241 (refs (filter ; only count a reference if its a binding
242 (lambda (x) (assoc x orig-bs))
243 (references (cdr bind))))
244 (edges (map (lambda (x) (cons vert x))
247 (rest (if (null? (cdr bs))
249 (go (cdr bs) orig-bs)))
250 (total-verts (cons vert (car rest)))
251 (total-edges (append edges (cdr rest)))]
252 (cons total-verts total-edges))))
255 (define (successors graph v)
259 (if (eqv? v (caar E))
260 (cons (cdar E) (go v (cdr E)))
264 ; takes in a graph (pair of vertices, edges)
265 ; returns a list of strongly connected components
267 ; ((x y w) . ((x . y) (x . w) (w . x))
277 ; this uses tarjan's algorithm, to get reverse
278 ; topological sorting for free
281 (let* ([indices (make-hash-table)]
282 [lowlinks (make-hash-table)]
283 [on-stack (make-hash-table)]
289 (get-hash-table indices v #f))
291 (get-hash-table lowlinks v #f))
297 (put-hash-table! indices v current)
298 (put-hash-table! lowlinks v current)
299 (set! current (+ current 1))
301 (put-hash-table! on-stack v #t)
305 (if (not (hashtable-contains? indices w))
306 ; successor w has not been visited, recurse
309 (put-hash-table! lowlinks
311 (min (lowlink v) (lowlink w))))
312 ; successor w has been visited
313 (when (get-hash-table on-stack w #f)
314 (put-hash-table! lowlinks v (min (lowlink v) (index w))))))
315 (successors graph v))
317 (when (= (index v) (lowlink v))
320 (let ([w (pop! stack)])
321 (put-hash-table! on-stack w #f)
324 (cons w (new-scc)))))])
325 (set! result (cons scc result))))))])
328 (when (not (hashtable-contains? indices v)) ; v.index == -1
338 (append (range s (- n 1))
339 (list (+ s (- n 1))))))
341 (define (flat-map f . xs) (fold-left append '() (apply map (cons f xs))))
342 (define (repeat x n) (if (<= n 0) '()
343 (cons x (repeat x (- n 1)))))
348 ((_ s x) (set! s (cons x s)))))
352 ((_ s) (let ([x (car s)])