Re: How to recover whitespace from syntax->string

Laurent,

Thank you very much.  It probably would have taken me a long time on my 
own to think of the possibility that the port was at fault.


Jeff


On 4/9/21 4:29 AM, Laurent wrote:
> You need to enable line/character counting with `port-count-lines!`:
>
> #lang racket
> (require syntax/to-string)
>
> (define in (open-input-string "(comment\n  \"hello world\"\n  line)"))
> (port-count-lines! in)
> (syntax->string (read-syntax "mystring" in))
>
> ; -> "comment\n \"hello world\"\n line"
>
> On Fri, Apr 9, 2021 at 2:10 AM Jeff Henrikson <[email protected] 
> <mailto:[email protected]>> wrote:
>
>     Racket users,
>
>     I’m trying to read a scheme file, decorate a bit of window
>     dressing around the edges, and write the expressions to a new
>     file.  I’ve got the basic mechanism working with (read . . .) and
>     (pretty-write . . .), but of course that doesn’t preserve
>     linebreaks.  So now I’m trying to improve it to preserve
>     linebreaks.  It would be nice to preserve all whitespace, but I'll
>     settle for linebreaks.  The racket docs seem to suggest it is
>     possible:
>
>         2.6 Rendering Syntax Objects with Formatting
>          (require syntax/to-string)     package: base
>                 procedure
>                 (syntax->string stx-list) → string?
>               stx-list : (and/c syntax? stx-list?)
>         Builds a string with newlines and indenting according to the
>         source locations in stx-list; the outer pair of parens are not
>         rendered from stx-list.
>
>     However, when I evaluate:
>
>         (syntax->string (read-syntax "mystring" (open-input-string
>         "(comment\n  \"hello world\"\n line)")))
>
>     I get:
>
>         "comment\"hello world\"line"
>
>     which has no whitespace at all, not even the whitespace that is
>     necessary to separate the original tokens.
>
>     I get a similar behavior if I read-syntax from a file and apply
>     syntax->string to those values.
>
>     Does anyone know how to get syntax->string to recover the original
>     whitespace?
>
>     I'm using Racket 8.0 cs on Ubuntu 20.
>
>
>     Thanks in advance,
>
>
>     Jeff Henrikson
>
>
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