On Wed, Apr 11, 2012 at 3:36 PM, Timothy Nelson <tbnel...@gmail.com> wrote:
>
> I'd like to write a function that consumes an s-expression and produces a
> struct -- something similar to building a tree struct out of a tree sexp. In
> the past, I've always used match for this kind of sexp manipulation.
> However, if I have a match clause within a function like this:
>
> (: my-func (Sexp -> mystruct))
> (define (my-func s)
> (match s
> [(list args ...) (make-mystruct (map my-func args))]))
The problem here is that Typed Racket can't guess what type you mean
for `args' to have, so you have to tell it when you bind `args'. That
looks like this:
(: my-func (Sexp -> mystruct))
(define (my-func s)
(match s
[(list #{args : (Listof Sexp)} ...)
(make-mystruct (map my-func args))]))
which typechecks correctly for me.
--
sam th
sa...@ccs.neu.edu
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