[racket-dev] wrong syntax position and span when using unicode lambda character?

Did you turn out port-count-lines! on the port?

Robby

On Mon, Jun 11, 2012 at 6:57 PM, Stephen Chang <stchang at ccs.neu.edu> wrote:
> I have a drracket plugin that reads the contents of the definitions
> window as syntax and then traverses that syntax object so that for
> each subexpression e it prints
> 1) (syntax->datum e), and
> 2) the contents of the definitions window at starting at position
> (syntax-position e) and ending at (syntax-position e) + (syntax-span
> e)
>
> I would expect each subexpression in the program to be printed twice
> and the plugin generally works as expected, except when I use the
> unicode lambda character.
>
>
> For example, if I have the program:
>
> #lang racket (add1 10)
>
> the (add1 10) syntax object correctly has position 14 and span 9 and
> the add1 syntax object correctly has position 15 and span 4.
>
>
> But for the program:
>
> #lang racket (λ (x) x)
>
> the (λ (x) x) syntax object has position 14 but span 11 (2 more than
> expected) and the λ syntax object has position 17 (again, 2 more than
> expected)
>
>
> Has anyone seen this behavior before?
>
>
> I'll try to distill my plugin to get something reproducible if it's
> not obvious what's going on.
>
> (I think that syntax positions start at 0 and editor positions start
> at 1 but I account for that so that's not the cause of the problem.)
>
> (I'm also aware that evaluating (syntax-span #'(λ (x) x)) in the repl
> correctly produces 9 so I don't know what's going on.)
>
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