20 ('closure 'closure) ; only available in codegen
21 ('static-string 'static-string) ; only available in codegen
22 ('stack 'stack) ; only available in codegen (tag that value is passed via stack)
24 ((builtin? x) 'builtin)
26 ((integer? x) 'int-literal)
27 ((boolean? x) 'bool-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 ('stack `(stack ,(cadr x) ,(f (caddr x))))
41 (define (ast-collect f x)
42 (define (inner y) (ast-collect f y))
45 (flat-map inner (let-bindings x))
46 (flat-map inner (let-body x)))]
49 ['lambda (append (f x)
50 (inner (lambda-body x)))]
52 (flat-map inner (cdr x)))]
57 (define (ast-find p x)
58 (define (inner y) (ast-find p y))
59 (define (any p x) (fold-left
60 (lambda (acc y) (if acc #t (p y)))
66 (apply either (cdr fs)))))
70 (any inner (let-bindings x))
71 (any inner (let-body x)))]
74 ['lambda (either (p x)
75 (inner (lambda-body x)))]
76 ['if (either (p x) (any inner (cdr x)))]
77 ['stack (either (p x) (inner (caddr x)))]
80 (define let-bindings cadr)
81 (define let-body cddr)
83 ; (let ([(foo a b) (foo 123 345)]) a)
86 ; (let ([a (foo~0 (foo 123 345)]
87 ; [b (foo~1 (foo 123 345)]) a)
88 (define (expand-pattern-matches program)
90 (define (pattern-match binding)
91 (let ([binding-name (car binding)]
92 [body (cadr binding)])
93 (if (eqv? (ast-type binding-name) 'var)
94 (list (list binding-name body))
96 (let* ([sum-name (car binding-name)]
97 [destructor (lambda (i) (dtor-name sum-name i))]
98 [products (cdr binding-name)]
100 [data-layouts (program-data-layouts program)]
102 [type (data-tor-type data-layouts sum-name)]
104 [sums (cdr (assoc type data-layouts))]
105 [sum (assoc sum-name sums)]
107 [expected-number (length (cdr sum))])
109 ; assert that we only do a let pattern match on an ADT with exactly one sum
110 (when (not (= 1 (length sums)))
111 (error #f (format "Cannot pattern match a ~a in a let since it has ~a possible constructors"
115 ; assert that there is the correct number of bindings
116 (when (not (= (length products)
118 (error #f (format "Got ~a bindings: expected ~a for ~a"
123 (flat-map (lambda (y i)
124 (pattern-match (list y `(,(destructor i) ,body))))
126 (range 0 (length products)))))))
128 ['let `(let ,(flat-map pattern-match (let-bindings x))
129 ,@(map go (let-body x)))]
130 [else (ast-traverse go x)]))
131 (program-map-exprs go program))
134 (and (list? x) (eq? (car x) 'lambda)))
136 (define (statement-type x)
139 (eqv? (car x) 'data)) 'data]
141 (eqv? (car x) 'define)) 'define]
145 ; (A ((foo (Int Bool))
147 (define (program-data-layouts program)
148 (map (lambda (x) (cons (car x) (cdr x))) ; convert to assoc list
149 (map cdr (filter (lambda (x) (eqv? (statement-type x) 'data))
152 (define (program-defines program)
153 (filter (lambda (x) (eqv? (statement-type x) 'defines))
156 (define (program-map-exprs f program)
158 (case (statement-type x)
163 (define (program-body program)
164 ; hack to have multi-expression bodies
166 ,@(filter (lambda (x) (eqv? (statement-type x) 'expr))
169 (define (data-tor-type data-layouts tor)
170 (let* ([tors (flat-map data-tors data-layouts)]
171 [info (cadr (assoc tor tors))])
174 ; a data tor is either a constructor or destructor for an ADT
175 ; data-tors returns constructors and destructors for a data-layout
176 ; (data A (foo Int Bool)
180 ; (foo . ((A foo constructor) . (abs Int (abs Bool A))))
181 ; (foo~0 . ((A foo 0) . (abs A Int)))
182 ; (foo~1 . ((A foo 1) . (abs A Bool)))
183 ; (bar . ((A bar constructor) . (abs Bool A)))
184 ; (bar~0 . ((A bar 0) . (abs A Bool)))
185 ; ------+-------------------------------------
188 (define (data-tors data-layout)
189 (define (constructor-type t products)
190 (fold-right (lambda (x acc) `(abs ,x ,acc)) t products))
192 (define (destructor ctor-name prod-type part-type index)
193 (let ([name (dtor-name ctor-name index)])
194 (cons name (cons (list prod-type ctor-name index) `(abs ,prod-type ,part-type)))))
196 (let ([type-name (car data-layout)]
197 [ctors (cdr data-layout)])
200 (let* ([ctor-name (car ctor)]
201 [products (cdr ctor)]
203 [maker (cons ctor-name (cons (list type-name ctor-name 'constructor) (constructor-type type-name products)))]
205 [dtors (map (lambda (t i) (destructor ctor-name type-name t i))
207 (range 0 (length products)))])
208 (cons maker (append dtors acc))))
212 ; creates a type environment for a given adt definition
213 (define (data-tors-type-env data-layout)
214 (map (lambda (x) (cons (car x) (cddr x))) (data-tors data-layout)))
216 (define (dtor-name ctor-name index)
218 (string-append (symbol->string ctor-name)
220 (number->string index))))
222 ; for use in normalized form
223 (define lambda-arg caadr)
225 (define lambda-args cadr)
226 (define lambda-body caddr)
228 (define (references prog)
237 (define (go bs orig-bs)
240 (let* [(bind (car bs))
243 (refs (filter ; only count a reference if its a binding
244 (lambda (x) (assoc x orig-bs))
245 (references (cdr bind))))
246 (edges (map (lambda (x) (cons vert x))
249 (rest (if (null? (cdr bs))
251 (go (cdr bs) orig-bs)))
252 (total-verts (cons vert (car rest)))
253 (total-edges (append edges (cdr rest)))]
254 (cons total-verts total-edges))))
257 (define (successors graph v)
261 (if (eqv? v (caar E))
262 (cons (cdar E) (go v (cdr E)))
266 ; takes in a graph (pair of vertices, edges)
267 ; returns a list of strongly connected components
269 ; ((x y w) . ((x . y) (x . w) (w . x))
279 ; this uses tarjan's algorithm, to get reverse
280 ; topological sorting for free
283 (let* ([indices (make-hash-table)]
284 [lowlinks (make-hash-table)]
285 [on-stack (make-hash-table)]
291 (get-hash-table indices v #f))
293 (get-hash-table lowlinks v #f))
299 (put-hash-table! indices v current)
300 (put-hash-table! lowlinks v current)
301 (set! current (+ current 1))
303 (put-hash-table! on-stack v #t)
307 (if (not (hashtable-contains? indices w))
308 ; successor w has not been visited, recurse
311 (put-hash-table! lowlinks
313 (min (lowlink v) (lowlink w))))
314 ; successor w has been visited
315 (when (get-hash-table on-stack w #f)
316 (put-hash-table! lowlinks v (min (lowlink v) (index w))))))
317 (successors graph v))
319 (when (= (index v) (lowlink v))
322 (let ([w (pop! stack)])
323 (put-hash-table! on-stack w #f)
326 (cons w (new-scc)))))])
327 (set! result (cons scc result))))))])
330 (when (not (hashtable-contains? indices v)) ; v.index == -1