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jacob
2026-05-26 10:04:15 -04:00
parent df4462b436
commit c3a09556b3
1 changed files with 215 additions and 167 deletions
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15-compilation-part-2/main.rkt
+124 -76
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@@ -15,7 +15,7 @@
| { <TOY> <TOY> ... }
|#
(define-type BINDINGS (Listof (Listof Symbol)))
(define-type BINDINGS = (Listof (Listof Symbol)))
;; A matching abstract syntax tree datatype:
(define-type TOY
@@ -36,6 +36,32 @@
(and (not (member (first xs) (rest xs)))
(unique-list? (rest xs)))))
; Parametric types having to end in '-of' is dumb.
(define-type (Perhapsof A)
[Some A]
[None])
(: index-of : Symbol (Listof Symbol) -> (Perhapsof Natural))
(define (index-of name names)
(: loop : (Listof Symbol) Natural -> (Perhapsof Natural))
(define (loop remaining idx)
(cond [(null? remaining) (None)]
[(symbol=? name (first remaining)) (Some idx)]
[else (loop (rest remaining) (add1 idx))]))
(loop names 0))
(: find-index : Symbol BINDINGS -> (Perhapsof (List Natural Natural)))
(define (find-index name bindings)
(: loop : BINDINGS Natural -> (Perhapsof (List Natural Natural)))
(define (loop rest-bindings binding-idx)
(cond [(null? rest-bindings) (None)]
[else
(let ([name-idx (index-of name (first rest-bindings))])
(cases name-idx
[(Some idx-in-scope) (Some (list binding-idx idx-in-scope))]
[(None) (loop (rest rest-bindings) (add1 binding-idx))]))]))
(loop bindings 0))
(: parse-sexpr : Sexpr -> TOY)
;; parses s-expressions into TOYs
(define (parse-sexpr sexpr)
@@ -87,12 +113,7 @@
;;; ==================================================================
;;; Values and environments
(define-type ENV
[EmptyEnv]
[FrameEnv FRAME ENV])
;; a frame is an association list of names and values.
(define-type FRAME = (Listof (List Symbol (Boxof VAL))))
(define-type ENV = (Listof (Listof (Boxof VAL))))
(define-type VAL
[BogusV]
@@ -103,48 +124,44 @@
;; a single bogus value to use wherever needed
(define the-bogus-value (BogusV))
(: raw-extend : (Listof Symbol) (Listof (Boxof VAL)) ENV -> ENV)
;; extends an environment with a new frame, given names and value
;; boxes
(define (raw-extend names boxed-values env)
(if (= (length names) (length boxed-values))
(FrameEnv (map (lambda ([name : Symbol] [boxed-val : (Boxof VAL)])
(list name boxed-val))
names boxed-values)
env)
(error 'raw-extend "arity mismatch for names: ~s" names)))
(: extend : (Listof Symbol) (Listof VAL) ENV -> ENV)
(: extend : (Listof VAL) ENV -> ENV)
;; extends an environment with a new frame (given plain values).
(define (extend names values env)
(raw-extend names (map (inst box VAL) values) env))
(cons (map (inst box VAL) values) env))
(: extend-rec : (Listof Symbol) (Listof (ENV -> VAL)) ENV -> ENV)
(: extend-rec : (Listof (ENV -> VAL)) ENV -> ENV)
;; extends an environment with a new recursive frame (given compiled
;; expressions).
(define (extend-rec names compiled-exprs env)
(define new-env
(extend names
(map (lambda (_) the-bogus-value) compiled-exprs)
env))
(define (extend-rec compiled-exprs env)
(define new-boxes
(map (λ (_) (box the-bogus-value)) compiled-exprs))
(define new-frame new-boxes)
(define new-env (cons new-frame env))
;; note: no need to check the lengths here, since this is only
;; called for `bindrec', and the syntax make it impossible to have
;; different lengths
(for-each (lambda ([name : Symbol] [compiled : (ENV -> VAL)])
(set-box! (lookup name new-env) (compiled new-env)))
names compiled-exprs)
(for-each (lambda ([boxed-val : (Boxof VAL)] [compiled : (ENV -> VAL)])
(set-box! boxed-val (compiled new-env)))
new-boxes compiled-exprs)
new-env)
(: lookup : Symbol ENV -> (Boxof VAL))
;; looks for a name in an environment, searching through each frame.
(define (lookup name env)
(cases env
[(EmptyEnv) (error 'lookup "no binding for ~s" name)]
[(FrameEnv frame rest)
(let ([cell (assq name frame)])
(if cell
(second cell)
(lookup name rest)))]))
(: framerefbox : (Listof (Boxof VAL)) Natural -> (Boxof VAL))
;; Gets you the box at idx in the frame.
(define (framerefbox frame idx)
(if (null? frame)
(error 'framerefbox "no binding found for index ~s" idx)
(if (zero? idx)
(first frame)
(framerefbox (rest frame) (sub1 idx)))))
(: envrefbox : ENV Natural Natural -> (Boxof VAL))
;; Gets you the box at (frameidx, keyidx) in an environment.
(define (envrefbox env frameidx keyidx)
(if (null? env)
(error 'envrefbox "no binding found for frame index ~s" frameidx)
(if (zero? frameidx)
(framerefbox (first env) keyidx)
(envrefbox (rest env) (sub1 frameidx) keyidx))))
(: unwrap-rktv : VAL -> Any)
;; helper for `racket-func->prim-val': unwrap a RktV wrapper in
@@ -154,7 +171,7 @@
[(RktV v) v]
[else (error 'racket-func "bad input: ~s" x)]))
(: racket-func->prim-val : Function -> (Boxof VAL))
(: racket-func->prim-val : Function -> VAL)
;; converts a racket function to a primitive evaluator function which
;; is a PrimV holding a ((Listof VAL) -> VAL) function. (the
;; resulting function will use the list function as is, and it is the
@@ -162,13 +179,13 @@
;; bad number of arguments or bad input types.)
(define (racket-func->prim-val racket-func)
(define list-func (make-untyped-list-function racket-func))
(box (PrimV (lambda (args)
(RktV (list-func (map unwrap-rktv args)))))))
(PrimV (lambda (args)
(RktV (list-func (map unwrap-rktv args))))))
;; The global environment has a few primitives:
(: global-environment : ENV)
(: global-environment : (Listof (List Symbol VAL)))
(define global-environment
(FrameEnv (list (list '+ (racket-func->prim-val +))
(list (list '+ (racket-func->prim-val +))
(list '- (racket-func->prim-val -))
(list '* (racket-func->prim-val *))
(list '/ (racket-func->prim-val /))
@@ -176,9 +193,15 @@
(list '> (racket-func->prim-val >))
(list '= (racket-func->prim-val =))
;; values
(list 'true (box (RktV #t)))
(list 'false (box (RktV #f))))
(EmptyEnv)))
(list 'true (RktV #t))
(list 'false (RktV #f))))
(: global-lookup : Symbol -> VAL)
(define (global-lookup name)
(let ([cell (assq name global-environment)])
(if cell
(second cell)
(error 'global-lookup "no binding for ~s" name))))
;;; ==================================================================
;;; Compilation
@@ -208,9 +231,14 @@
(define (compile-getter expr)
(cases expr
[(Id name)
(lambda ([env : ENV]) (lookup name env))]
(cases (find-index name bin)
[(Some location) (λ ([env : ENV])
(envrefbox env (first location) (second location)))]
[(None) (if (assq name global-environment)
(λ ([_ : ENV]) (error 'call "rfun can't use global ~s" name))
(error 'compile-get-boxes "no binding for ~s" name))])]
[else
(lambda ([env : ENV])
(lambda ([_ : ENV])
(error 'call "rfun application with a non-identifier ~s"
expr))]))
(unless (unbox compiler-enabled?)
@@ -229,35 +257,49 @@
(lambda (compiled) (compiled env)))
(unless (unbox compiler-enabled?)
(error 'compile "compiler disabled"))
(: compile* : TOY -> (ENV -> VAL))
(define (compile* expr*) (compile expr* bin))
(cases expr
[(Num n) (lambda ([env : ENV]) (RktV n))]
[(Id name) (lambda ([env : ENV]) (unbox (lookup name env)))]
[(Id name)
(cases (find-index name bin)
[(Some location) (λ ([env : ENV]) (unbox (envrefbox env (first location) (second location))))]
[(None) (let ([global-val (global-lookup name)])
(λ ([_ : ENV]) global-val))])]
[(Set name new)
(define compiled-new (compile new))
(lambda ([env : ENV])
(set-box! (lookup name env) (compiled-new env))
(define compiled-new (compile new bin))
(cases (find-index name bin)
[(Some location)
(λ ([env : ENV])
(set-box! (envrefbox env (first location) (second location))
(compiled-new env))
the-bogus-value)]
[(None)
(let ([_ (global-lookup name)])
(λ ([_ : ENV]) (error 'compile "can't set flobal binding for ~s" name)))])]
[(Bind names exprs bound-body)
(define compiled-exprs (map compile exprs))
(define compiled-body (compile-body bound-body))
(define compiled-exprs (map compile* exprs))
(define compiled-body (compile-body bound-body (cons names bin)))
(lambda ([env : ENV])
(compiled-body
(extend names (map (caller env) compiled-exprs) env)))]
(extend (map (caller env) compiled-exprs) env)))]
[(BindRec names exprs bound-body)
(define compiled-exprs (map compile exprs))
(define compiled-body (compile-body bound-body))
(: ah : (Listof (Listof Symbol)))
(define ah (cons names bin))
(define compiled-exprs (map (λ ([x : TOY]) (compile x ah)) exprs))
(define compiled-body (compile-body bound-body ah))
(lambda ([env : ENV])
(compiled-body (extend-rec names compiled-exprs env)))]
(compiled-body (extend-rec compiled-exprs env)))]
[(Fun names bound-body)
(define compiled-body (compile-body bound-body))
(define compiled-body (compile-body bound-body (cons names bin)))
(lambda ([env : ENV]) (FunV names compiled-body env #f))]
[(RFun names bound-body)
(define compiled-body (compile-body bound-body))
(define compiled-body (compile-body bound-body (cons names bin)))
(lambda ([env : ENV]) (FunV names compiled-body env #t))]
[(Call fun-expr arg-exprs)
(define compiled-fun (compile fun-expr))
(define compiled-args (map compile arg-exprs))
(define compiled-boxes-getter (compile-get-boxes arg-exprs))
(define compiled-fun (compile fun-expr bin))
(define compiled-args (map compile* arg-exprs))
(define compiled-boxes-getter (compile-get-boxes arg-exprs bin))
(lambda ([env : ENV])
(define fval (compiled-fun env))
;; delay evaluating the arguments
@@ -266,16 +308,14 @@
[(PrimV proc) (proc (arg-vals))]
[(FunV names compiled-body fun-env byref?)
(compiled-body (if byref?
(raw-extend names
(compiled-boxes-getter env)
fun-env)
(extend names (arg-vals) fun-env)))]
(cons (compiled-boxes-getter env) fun-env)
(extend (arg-vals) fun-env)))]
[else (error 'call "function call with a non-function: ~s"
fval)]))]
[(If cond-expr then-expr else-expr)
(define compiled-cond (compile cond-expr))
(define compiled-then (compile then-expr))
(define compiled-else (compile else-expr))
(define compiled-cond (compile cond-expr bin))
(define compiled-then (compile then-expr bin))
(define compiled-else (compile else-expr bin))
(lambda ([env : ENV])
((if (cases (compiled-cond env)
[(RktV v) v] ; Racket value => use as boolean
@@ -288,9 +328,9 @@
;; compiles and runs a TOY program contained in a string
(define (run str)
(set-box! compiler-enabled? #t)
(let ([compiled (compile (parse str))])
(let ([compiled (compile (parse str) '(()))])
(set-box! compiler-enabled? #f)
(let ([result (compiled global-environment)])
(let ([result (compiled '())])
(cases result
[(RktV v) v]
[else (error 'run "the program returned a bad value: ~s"
@@ -341,6 +381,8 @@
;; assignment tests
(test (run "{set! {+ x 1} x}") =error> "bad `set!' syntax")
(test (run "{bind {{x 1}} {set! x {+ x 1}} x}") => 2)
(test (run "{set! + 1}") =error> "set")
(test (run "{set! nope 1}") =error> "no binding")
;; `bindrec' tests
(test (run "{bindrec {x 6} x}") =error> "bad `bindrec' syntax")
@@ -384,13 +426,19 @@
(test (run "{{rfun {x} x} {/ 4 0}}") =error> "non-identifier")
(test (run "{5 {/ 6 0}}") =error> "non-function")
(test (index-of 'k '(a b k c)) => (Some 2))
(test (index-of 'k '(a b c)) => (None))
(test (find-index 'k '((a b) (k y) (k z))) => (Some '(1 0)))
(test (find-index 'a '((a b) (k y))) => (Some '(0 0)))
(test (find-index 'q '((a b) (k y))) => (None))
;; test compiler-disabled flag, for complete coverage
;; (these tests must use the functions instead of the toplevel `run',
;; since there is no way to get this error otherwise, this indicates
;; that this error should not occur outside of our code -- it is an
;; internal error check)
(test (compile (Num 1)) =error> "compiler disabled")
(test (compile-body (list (Num 1))) =error> "compiler disabled")
(test (compile-get-boxes (list (Num 1))) =error> "compiler disabled")
(test (compile (Num 1) '(())) =error> "compiler disabled")
(test (compile-body (list (Num 1)) '(())) =error> "compiler disabled")
(test (compile-get-boxes (list (Num 1)) '(())) =error> "compiler disabled")
;;; ==================================================================