r5rs niternal definitions as r5rs letrec instead mz letrec
svn: r9286
This commit is contained in:
Matthew Flatt
parent
aa1a56c3fd
commit
b372856777
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@ -1,7 +1,7 @@
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(module main scheme/base
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(require scheme/mpair
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(for-syntax scheme/base)
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(for-syntax scheme/base syntax/kerncase)
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(only-in mzscheme transcript-on transcript-off))
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(provide (for-syntax syntax-rules ...)
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@ -227,47 +227,60 @@
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;; Copied from R5rS, but with an added `let' around body,
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;; and with optimization for precedure letrecs
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(define undefined (letrec ([u u]) u))
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(define-syntax r5rs:letrec
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(syntax-rules (r5rs:lambda)
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((r5rs:letrec ((var1 (r5rs:lambda . _rest)) ...) body ...)
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(letrec ((var1 (r5rs:lambda . _rest)) ...) body ...))
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(define-for-syntax (immediate-value? stx)
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(let ([v (syntax-e stx)])
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(or (number? v)
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(boolean? v)
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(string? v)
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(syntax-case stx (r5rs:lambda quote r5rs:quote #%datum)
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[(r5rs:lambda . _rest) #t]
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[(quote . _) #t]
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[(r5rs:quote . _) #t]
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[(#%datum . _) #t]
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[_ #f]))))
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(define-syntax (r5rs:letrec stx)
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(syntax-case stx (r5rs:lambda)
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((r5rs:letrec ((var1 rhs) ...) body ...)
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(andmap immediate-value? (syntax->list #'(rhs ...)))
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#'(letrec ((var1 rhs) ...) (r5rs:body body ...)))
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((r5rs:letrec ((var1 init1) ...) body ...)
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(r5rs:letrec "generate_temp_names"
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(var1 ...)
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()
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((var1 init1) ...)
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body ...))
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#'(r5rs:letrec "generate_temp_names"
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(var1 ...)
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()
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((var1 init1) ...)
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body ...))
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((r5rs:letrec "generate_temp_names"
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()
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(temp1 ...)
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((var1 init1) ...)
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body ...)
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(let ((var1 undefined) ...)
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(let ((temp1 init1) ...)
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(set! var1 temp1)
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...
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(let ()
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body ...))))
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()
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(temp1 ...)
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((var1 init1) ...)
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body ...)
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#'(let ((var1 undefined) ...)
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(let ((temp1 init1) ...)
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(set! var1 temp1)
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...
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(let ()
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(r5rs:body
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body ...)))))
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((r5rs:letrec "generate_temp_names"
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(x y ...)
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(temp ...)
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((var1 init1) ...)
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body ...)
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(r5rs:letrec "generate_temp_names"
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(y ...)
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(newtemp temp ...)
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((var1 init1) ...)
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body ...))))
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(x y ...)
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(temp ...)
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((var1 init1) ...)
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body ...)
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#'(r5rs:letrec "generate_temp_names"
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(y ...)
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(newtemp temp ...)
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((var1 init1) ...)
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body ...))))
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(define-syntax r5rs:lambda
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;; Convert rest-arg list to mlist:
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(syntax-rules ()
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[(_ (id ...) . body)
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(#%plain-lambda (id ...) . body)]
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(#%plain-lambda (id ...) (r5rs:body . body))]
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[(_ (id ... . rest) . body)
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(#%plain-lambda (id ... . rest)
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(let ([rest (list->mlist rest)])
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. body))]))
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(r5rs:body . body)))]))
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(define-syntax (r5rs:define stx)
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;; Use r5rs:lambda
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@ -283,6 +296,12 @@
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(define . rest))]))
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(define-syntax (r5rs:define-syntax stx)
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;; Disallow in internal-definition contexts:
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(when (pair? (syntax-local-context))
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(raise-syntax-error
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#f
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"disallowed as an internal definition"
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stx))
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(syntax-case stx ()
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[(_ id expr)
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(identifier? #'id)
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@ -316,6 +335,98 @@
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(apply values (promise-p p)))
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(apply values v))))
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(define-syntax r5rs:let
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(syntax-rules ()
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[(_ (binding ...) . body)
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(let (binding ...) (r5rs:body . body))]
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[(_ id (binding ...) . body)
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(let id (binding ...) (r5rs:body . body))]))
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(define-syntax-rule (r5rs:let* bindings . body)
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(let* bindings (r5rs:body . body)))
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(define-syntax-rule (r5rs:let-syntax bindings . body)
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(let-syntax bindings (r5rs:body . body)))
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(define-syntax-rule (r5rs:letrec-syntax bindings . body)
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(letrec-syntax bindings (r5rs:body . body)))
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(define-syntax (r5rs:body stx)
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(syntax-case stx (let)
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[(_ (let () . body))
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#'(let () . body)]
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[_
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;; Convert internal definitions to `r5rs:letrec', as opposed
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;; to `letrec'.
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(let ([def-ctx (syntax-local-make-definition-context)]
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[ctx (list (gensym 'intdef))]
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[kernel-forms (kernel-form-identifier-list)]
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[init-exprs (let ([v (syntax->list stx)])
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(unless v
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(raise-syntax-error #f "bad syntax" stx))
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(cdr v))])
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(with-syntax ([(exprs ((id ...) ...) (rhs ...) (stx-ids ...) (stx-rhs ...))
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(let loop ([exprs init-exprs]
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[idss null][rhss null]
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[stx-idss null][stx-rhss null])
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(if (null? exprs)
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(raise-syntax-error
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#f
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"no expression in body"
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stx)
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(let ([expr (local-expand (car exprs) ctx kernel-forms def-ctx)])
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(syntax-case expr (begin define-syntaxes define-values)
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[(begin . rest)
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(let ([l (syntax->list #'rest)])
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(if l
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(loop (append l exprs) idss rhss stx-idss stx-rhss)
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(raise-syntax-error #f expr "bad syntax")))]
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[(define-syntaxes (id ...) rhs)
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(andmap identifier? (syntax->list #'(id ...)))
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(with-syntax ([rhs (local-transformer-expand
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#'rhs
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'expression
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null)])
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(syntax-local-bind-syntaxes
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(syntax->list #'(id ...))
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#'rhs def-ctx)
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(loop (cdr exprs)
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idss rhss
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(cons #'(id ...) stx-idss)
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(cons #'rhs stx-rhss)))]
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[(define-values (id ...) rhs)
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(andmap identifier? (syntax->list #'(id ...)))
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(let ([ids (syntax->list #'(id ...))])
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(syntax-local-bind-syntaxes ids #f def-ctx)
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(loop (cdr exprs)
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(cons #'(id ...) idss)
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(cons #'rhs rhss)
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stx-idss stx-rhss))]
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[else
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(list (cons expr
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(map (lambda (expr)
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(local-expand expr ctx kernel-forms def-ctx))
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(cdr exprs)))
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(reverse idss) (reverse rhss)
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(reverse stx-idss) (reverse stx-rhss))]))))])
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(if (and (null? (syntax-e #'(stx-rhs ...)))
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(andmap (lambda (ids)
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(= 1 (length (syntax->list ids))))
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(syntax->list #'((id ...) ...))))
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;; This is the normal case: use `r5rs:letrec':
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#`(r5rs:letrec ([id ... rhs] ...)
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(let () . exprs))
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;; Unusual case: need to expand to `set!' manually:
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(with-syntax ([((tmp-id ...) ...)
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(map (lambda (ids)
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(generate-temporaries ids))
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(syntax->list #'((id ...) ...)))])
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#`(letrec-syntaxes+values
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([stx-ids stx-rhs] ...)
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([(id ...) (values (mk-undefined id) ...)] ...)
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(let-values ([(tmp-id ...) rhs] ...)
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(begin (set! id tmp-id) ...) ...
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. exprs))))))]))
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(define-syntax-rule (mk-undefined id) undefined)
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(provide unquote unquote-splicing
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(rename-out [r5rs:quote quote]
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[r5rs:quasiquote quasiquote]
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@ -324,10 +435,13 @@
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[r5rs:letrec letrec]
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[r5rs:define define]
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[r5rs:define-syntax define-syntax]
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[r5rs:delay delay])
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let and or cond case do
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let* begin set!
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let-syntax letrec-syntax
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[r5rs:delay delay]
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[r5rs:let let]
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[r5rs:let* let*]
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[r5rs:let-syntax let-syntax]
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[r5rs:letrec-syntax letrec-syntax])
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and or cond case do
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begin set!
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=> else
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;; We have to include the following MzScheme-isms to do anything,
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