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Make syntax' print as syntax' not as #'

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Thanks to Matthew Flatt for noticing the problem and
providing a solution!
This commit is contained in:
Greg Hendershott 2012-10-28 10:48:02 -04:00
parent b05abb9f98
commit 2371243806
1 changed files with 18 additions and 1 deletions
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19
main.rkt
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@ -2,7 +2,9 @@
@(require racket/sandbox @(require racket/sandbox
scribble/eval scribble/eval
scribble/racket
racket/date racket/date
(for-syntax racket/base)
(for-label racket) (for-label racket)
(for-label racket/stxparam) (for-label racket/stxparam)
(for-label syntax/parse)) (for-label syntax/parse))
@ -136,11 +138,15 @@ returns syntax. It transforms syntax.
Here's a transformer function that ignores its input syntax, and Here's a transformer function that ignores its input syntax, and
always outputs syntax for a string literal: always outputs syntax for a string literal:
@(let-syntax([syntax (make-element-id-transformer
(lambda (stx)
#'@racket[syntax]))]) ;print as syntax not #'
@i[ @i[
(define-syntax foo (define-syntax foo
(lambda (stx) (lambda (stx)
(syntax "I am foo"))) (syntax "I am foo")))
] ]
)
Using it: Using it:
@ -168,11 +174,15 @@ That shorthand lets you avoid typing @racket[lambda] and some parentheses.
Well there is a similar shorthand for @racket[define-syntax]: Well there is a similar shorthand for @racket[define-syntax]:
@(let-syntax([syntax (make-element-id-transformer
(lambda (stx)
#'@racket[syntax]))]) ;print as syntax not #'
@i[ @i[
(define-syntax (also-foo stx) (define-syntax (also-foo stx)
(syntax "I am also foo")) (syntax "I am also foo"))
(also-foo) (also-foo)
] ]
)
What we want to remember is that this is simply shorthand. We are What we want to remember is that this is simply shorthand. We are
still defining a transformer function, which takes syntax and returns still defining a transformer function, which takes syntax and returns
@ -182,12 +192,17 @@ basic idea. It's not magic.
Speaking of shorthand, there is also a shorthand for @racket[syntax], Speaking of shorthand, there is also a shorthand for @racket[syntax],
which is @tt{#'}: which is @tt{#'}:
@margin-note{@tt{#'} is short for @racket[syntax] much like
@tt{'} is short for @racket[quote].}
@i[ @i[
(define-syntax (quoted-foo stx) (define-syntax (quoted-foo stx)
#'"I am also foo, using #' instead of syntax") #'"I am also foo, using #' instead of syntax")
(quoted-foo) (quoted-foo)
] ]
We'll use the #' shorthand from now on.
Of course, we can emit syntax that is more interesting than a Of course, we can emit syntax that is more interesting than a
string literal. How about returning @racket[(displayln "hi")]? string literal. How about returning @racket[(displayln "hi")]?
@ -958,7 +973,9 @@ before PLT Scheme was renamed to Racket.
After initially wondering if I was asking the wrong question and After initially wondering if I was asking the wrong question and
conflating two different issues :), Shriram Krishnamurthi looked at an conflating two different issues :), Shriram Krishnamurthi looked at an
early draft and encouraged me to keep going. Sam Tobin-Hochstadt and early draft and encouraged me to keep going. Sam Tobin-Hochstadt and
Robby Findler also encouraged me. Robby Findler also encouraged me. Matthew Flatt showed me how to make
a Scribble @racket[interaction] print @racket[syntax] as
@racket["syntax"] rather than as @racket["#'"].
Finally, I noticed something strange. After writing much of this, when Finally, I noticed something strange. After writing much of this, when
I returned to some parts of the Racket documentation, I noticed it had I returned to some parts of the Racket documentation, I noticed it had