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simplify stepper and fix unevaluated id bug

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This commit is contained in:
John Clements 2014-05-18 00:18:54 -07:00
parent a72b8d8a05
commit 89b96ef9f3
3 changed files with 19 additions and 11 deletions
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14
pkgs/htdp-pkgs/htdp-lib/stepper/DESIGN-NOTES
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@ -962,3 +962,17 @@ code, and works better, too.
Nice to be here again... Nice to be here again...
2010-12-04 2010-12-04
**************
How time flies. Small bug fixes; it's now illegal to refer to undefined
values. That is, (letrec ([a a]) 3) is illegal. This caused stepper
breakage, and I was worried that fixing this was going to require some
terrible deep surgery. In fact, though, it looks like this change
makes things *simpler*; it looks like I was going out of my way to
preserve the undefined values for situations where it might turn up in
student programs, and now I can omit that check.
2013-05-18
**************

15
pkgs/htdp-pkgs/htdp-lib/stepper/private/annotate.rkt
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@ -436,7 +436,7 @@
; wish me luck. ; wish me luck.
(define (let-abstraction stx output-identifier make-init-list) (define (let-abstraction stx output-identifier)
(with-syntax ([(_ ([(var ...) val] ...) . bodies) stx]) (with-syntax ([(_ ([(var ...) val] ...) . bodies) stx])
(match-let* (match-let*
([binding-sets (map syntax->list (syntax->list #'((var ...) ...)))] ([binding-sets (map syntax->list (syntax->list #'((var ...) ...)))]
@ -491,7 +491,7 @@
free-varref-sets-vals)) free-varref-sets-vals))
binding-list)] binding-list)]
[counter-id #`lifting-counter] [counter-id #`lifting-counter]
[unevaluated-list (make-init-list binding-list)] [unevaluated-list (map (lambda (b) *unevaluated*) binding-list)]
[outer-initialization [outer-initialization
#`([(#,@lifted-vars #,@binding-list #,let-counter) #`([(#,@lifted-vars #,@binding-list #,let-counter)
(values #,@(append (map (lambda (dc_binding) counter-id) (values #,@(append (map (lambda (dc_binding) counter-id)
@ -788,16 +788,9 @@
#,rolled-into-fakes)) #,rolled-into-fakes))
all-free-vars))] all-free-vars))]
[(let-values . _) [(let-values . _) (let-abstraction exp #`let-values)]
(let-abstraction exp
#`let-values
(lambda (bindings)
(map (lambda (_) *unevaluated*) bindings)))]
[(letrec-values . _) [(letrec-values . _) (let-abstraction exp #`letrec-values)]
(let-abstraction exp
#`letrec-values
(lambda (bindings) (map (lambda (b) #`#,b) bindings)))]
; $ ; $

1
pkgs/htdp-pkgs/htdp-lib/stepper/private/model.rkt
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@ -522,6 +522,7 @@
;; step through a single expanded expression. ;; step through a single expanded expression.
(define (step-through-expression expanded) (define (step-through-expression expanded)
(define annotated (a:annotate expanded break show-lambdas-as-lambdas?)) (define annotated (a:annotate expanded break show-lambdas-as-lambdas?))
#;(printf "annotated: ~s\n" annotated)
(parameterize ([test-engine:test-silence #t]) (parameterize ([test-engine:test-silence #t])
(eval-syntax annotated))) (eval-syntax annotated)))