I'm trying to use syntax-local-lift to lift the definition of a
structure to the top level.
syntax-local-lift-module-end-declaration doesn't work because it is
not guaranteed to be in an expression context, so I can't have a
define.
syntax-local-lift-expression doesn't work because it only works for
establishing a single binding, whereas a structure definition requires
3+2n bindings.
I thought that I might be able to simulate this:
#lang scheme
(require (for-syntax scheme/list))
(define-for-syntax (syntax-local-lift-expression/values how-many stx)
(define the-values-id
(syntax-local-lift-expression (quasisyntax/loc stx
(call-with-values #,stx (lambda the-values the-values)))))
(build-list
how-many
(lambda (which-value)
(syntax-local-lift-expression (quasisyntax/loc stx (list-ref
#,the-values-id #,which-value))))))
(define-syntax (testit stx)
(syntax-case stx ()
[(_)
(let ([the-values
(syntax-local-lift-expression/values 3 (syntax/loc stx
(values 1 2 3)))])
(syntax-local-lift-module-end-declaration
(quasisyntax/loc stx
(begin #,@(map (lambda (value-id)
(quasisyntax/loc stx
(printf "~S~n" #,value-id)))
the-values)))))
(syntax/loc stx (printf "Lifted~n"))]))
(testit)
But I cannot, because syntax-local-lift-expression puts things in the
reverse order of the calls. This is expanded in the macro stepper to:
(define-values (lifted.6:84) (#%app:85 list-ref:86 lifted.0:87 '2))
(define-values (lifted.4:88) (#%app:89 list-ref:86 lifted.0:87 '1))
(define-values (lifted.2:90) (#%app:91 list-ref:86 lifted.0:87 '0))
(define-values (lifted.0:87)
(#%app:92
call-with-values:86
(#%app:93 values:86 (quote 1) (quote 2) (quote 3))
(lambda:94 the-values:86 the-values:86)))
(#%app:96 call-with-values:96 (lambda:96 () (#%app:95 printf:86
(quote "Lifted~n"))) print-values:96)
(#%app:97 printf:86 (quote "~S~n") lifted.2:90)
(#%app:98 printf:86 (quote "~S~n") lifted.4:88)
(#%app:99 printf:86 (quote "~S~n") lifted.6:84)
So... can we get either of these changed? Either a native
syntax-local-lift-expressions or put the syntax-local-lift-expression
calls in the order they are given, rather than the reverse?
Jay
--
Jay McCarthy <j...@cs.byu.edu>
Assistant Professor / Brigham Young University
http://teammccarthy.org/jay
"The glory of God is Intelligence" - D&C 93
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