Greetings.
(this is a separate typed-racket question, and I think distinct from the
questions I was asking last month)
I don't seem to be able to specify a type for a function with rest arguments
and optional keywords. The following fails to typecheck (Racket 5.3.3)
(: appender (String String * [#:k String] -> String))
(define (appender s1 #:k (v #f) . sx)
(let loop ((l sx)
(res (string-append s1 (or v "-x-"))))
(if (null? l)
res
(loop (cdr l) (string-append res (car l))))))
-> Type Checker: Expected a function of type (case-> (String True String String
* -> String) (False False String String * -> String)), but got a function with
the wrong arity in: (define (appender s1 #:k (v #f) . sx) (let loop ((l sx)
(res (string-append s1 (or v "-x-")))) (if (null? l) res (loop (cdr l)
(string-append res (car l))))))
Similar functions work, with types (: appender (String String * -> String)) and
(: appender (String String [#:k String] -> String)), so I don't think I'm
messing up the syntax.
Best wishes,
Norman
--
Norman Gray : http://nxg.me.uk
SUPA School of Physics and Astronomy, University of Glasgow, UK
____________________
Racket Users list:
http://lists.racket-lang.org/users
