Re: [racket-users] macro definitions with #lang racket/base vs #lang racket

[NeverTooOldToCode]

Thank you! 
I see now that the very same question was already asked on this list in 2015, 
by a compatriot of mine no less. It didn't show up in my online searches 
beforehand, the keyword missing was "transformer environment".

On Tuesday, March 14, 2017 at 1:05:31 PM UTC+1, Philip McGrath wrote:
> #lang racket also provides racket/base in the transformer environment.
> 
> 
> 
> -Philip

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Re: [racket-users] macro definitions with #lang racket/base vs #lang racket

[Philip McGrath]

#lang racket also provides racket/base in the transformer environment.

-Philip

On Tue, Mar 14, 2017 at 5:45 AM, NeverTooOldToCode 
wrote:

> From Fear of Macros again, all input in the DrRacket definition window.
>
> This works:
>
> #lang racket/base
>
> (require (for-syntax racket/base))
>
> (define-syntax (show-me stx)
>   (display stx)
>   #'(void))
>
> If you mouse-hover over the keywords, define-syntax is imported from #lang
> racket/base, and display and #' are imported (require (for-syntax
> racket/base)).
> Because display and #' are needed at compile time, not run time.
>
> Therefore, logically, this doesn't work:
>
> #lang racket/base
>
> (define-syntax (show-me stx)
>   (display stx)
>   #'(void))
>
> Gives the error:
> display: unbound identifier in the transformer environment; also, no #%app
> syntax transformer is bound in: display
> And if we remove the display statement, the same error for #'
>
> So far so good.
>
> BUT
>
> Why does this work?
>
> #lang racket
>
> (define-syntax (show-me stx)
>   (display stx)
>   #'(void))
>
> Now define-syntax *and* display *and* #' are directly imported from #lang
> racket. What about compile time vs run time? What does #lang racket do
> apart from including many libraries on top of racket/base?
>
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