On Dec 10, 2015, at 1:15 PM, Jonathan Brachthäuser <[email protected]> wrote:
> In DrRacket 6.2.1 when using the `match` construct as defined in the > abstraction teachpack together with posn a strange problem appears. > > When choosing BSL as language the following code just works as expected: > > ``` > (require 2htdp/abstraction) > (match (make-posn 1 2) [(posn x y) (+ x y)]) > ``` > > yields `3`. > > However when choosing "BSL with list abbreviation" the above code gives: > > ``` > ... (posn x y) ... > function call: expected a function after the open parenthesis, but found a > part > ``` > > We can work around the error by using `my-posn` instead (defined below) > > ``` > (define-struct my-posn (x y)) > ``` > > Is there any explanation why this happens? Is the abstraction teachpack not > designed to work with "BSL with list abbrv" ? No, 2htdp/abstraction is designed to work with ISL and ISL+. The above problem is precisely why it doesn't work in BSL and BSL+. (There is a second problem, which escapes me right now.) -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
