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-expr 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)))]
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-expr cadr)
92 (define case-cases cddr)
94 ; (let ([(foo a b) (foo 123 345)]) a)
97 ; (let ([a (foo~0 (foo 123 345)]
98 ; [b (foo~1 (foo 123 345)]) a)
99 (define (expand-pattern-matches program)
101 (define (pattern-match binding)
102 (let ([binding-name (car binding)]
103 [body (cadr binding)])
104 (if (eqv? (ast-type binding-name) 'var)
105 (list (list binding-name body))
107 (let* ([sum-name (car binding-name)]
108 [destructor (lambda (i) (dtor-name sum-name i))]
109 [products (cdr binding-name)]
111 [data-layouts (program-data-layouts program)]
113 [type (data-tor-type data-layouts sum-name)]
115 [sums (cdr (assoc type data-layouts))]
116 [sum (assoc sum-name sums)]
118 [expected-number (length (cdr sum))])
120 ; assert that we only do a let pattern match on an ADT with exactly one sum
121 (when (not (= 1 (length sums)))
122 (error #f (format "Cannot pattern match a ~a in a let since it has ~a possible constructors"
126 ; assert that there is the correct number of bindings
127 (when (not (= (length products)
129 (error #f (format "Got ~a bindings: expected ~a for ~a"
134 (flat-map (lambda (y i)
135 (pattern-match (list y `(,(destructor i) ,body))))
137 (range 0 (length products)))))))
139 ['let `(let ,(flat-map pattern-match (let-bindings x))
140 ,@(map go (let-body x)))]
141 [else (ast-traverse go x)]))
142 (program-map-exprs go program))
145 (and (list? x) (eq? (car x) 'lambda)))
147 (define (statement-type x)
150 (eqv? (car x) 'data)) 'data]
152 (eqv? (car x) 'define)) 'define]
156 ; (A ((foo (Int Bool))
158 (define (program-data-layouts program)
159 (map (lambda (x) (cons (car x) (cdr x))) ; convert to assoc list
160 (map cdr (filter (lambda (x) (eqv? (statement-type x) 'data))
163 (define (program-defines program)
164 (filter (lambda (x) (eqv? (statement-type x) 'defines))
167 (define (program-map-exprs f program)
169 (case (statement-type x)
174 (define (program-body program)
175 ; hack to have multi-expression bodies
177 ,@(filter (lambda (x) (eqv? (statement-type x) 'expr))
180 (define (data-tor-type data-layouts tor)
181 (let* ([tors (flat-map data-tors data-layouts)]
182 [info (cadr (assoc tor tors))])
185 ; a data tor is either a constructor or destructor for an ADT
186 ; data-tors returns constructors and destructors for a data-layout
187 ; (data A (foo Int Bool)
191 ; (foo . ((A foo constructor) . (abs Int (abs Bool A))))
192 ; (foo~0 . ((A foo 0 Int) . (abs A Int)))
193 ; (foo~1 . ((A foo 1 Bool) . (abs A Bool)))
194 ; (bar . ((A bar constructor) . (abs Bool A)))
195 ; (bar~0 . ((A bar 0 Bool) . (abs A Bool)))
196 ; ------+-------------------------------------
199 (define (data-tors data-layout)
200 (define (constructor-type t products)
201 (fold-right (lambda (x acc) `(abs ,x ,acc)) t products))
203 (define (destructor ctor-name prod-type part-type index)
204 (let* ([name (dtor-name ctor-name index)]
205 [info (list prod-type ctor-name index part-type)])
206 (cons name (cons info `(abs ,prod-type ,part-type)))))
208 (let ([type-name (car data-layout)]
209 [ctors (cdr data-layout)])
212 (let* ([ctor-name (car ctor)]
213 [products (cdr ctor)]
215 [maker (cons ctor-name (cons (list type-name ctor-name 'constructor) (constructor-type type-name products)))]
217 [dtors (map (lambda (t i) (destructor ctor-name type-name t i))
219 (range 0 (length products)))])
220 (cons maker (append dtors acc))))
224 ; creates a type environment for a given adt definition
225 (define (data-tors-type-env data-layout)
226 (map (lambda (x) (cons (car x) (cddr x))) (data-tors data-layout)))
228 (define (dtor-name ctor-name index)
230 (string-append (symbol->string ctor-name)
232 (number->string index))))
234 ; for use in normalized form
235 (define lambda-arg caadr)
237 (define lambda-args cadr)
238 (define lambda-body caddr)
240 (define (references prog)
249 (define (go bs orig-bs)
252 (let* [(bind (car bs))
255 (refs (filter ; only count a reference if its a binding
256 (lambda (x) (assoc x orig-bs))
257 (references (cdr bind))))
258 (edges (map (lambda (x) (cons vert x))
261 (rest (if (null? (cdr bs))
263 (go (cdr bs) orig-bs)))
264 (total-verts (cons vert (car rest)))
265 (total-edges (append edges (cdr rest)))]
266 (cons total-verts total-edges))))
269 (define (successors graph v)
273 (if (eqv? v (caar E))
274 (cons (cdar E) (go v (cdr E)))
278 ; takes in a graph (pair of vertices, edges)
279 ; returns a list of strongly connected components
281 ; ((x y w) . ((x . y) (x . w) (w . x))
291 ; this uses tarjan's algorithm, to get reverse
292 ; topological sorting for free
295 (let* ([indices (make-hash-table)]
296 [lowlinks (make-hash-table)]
297 [on-stack (make-hash-table)]
303 (get-hash-table indices v #f))
305 (get-hash-table lowlinks v #f))
311 (put-hash-table! indices v current)
312 (put-hash-table! lowlinks v current)
313 (set! current (+ current 1))
315 (put-hash-table! on-stack v #t)
319 (if (not (hashtable-contains? indices w))
320 ; successor w has not been visited, recurse
323 (put-hash-table! lowlinks
325 (min (lowlink v) (lowlink w))))
326 ; successor w has been visited
327 (when (get-hash-table on-stack w #f)
328 (put-hash-table! lowlinks v (min (lowlink v) (index w))))))
329 (successors graph v))
331 (when (= (index v) (lowlink v))
334 (let ([w (pop! stack)])
335 (put-hash-table! on-stack w #f)
338 (cons w (new-scc)))))])
339 (set! result (cons scc result))))))])
342 (when (not (hashtable-contains? indices v)) ; v.index == -1