On Jan 6, 2014, at 11:59 AM, Matthew Flatt <mfl...@cs.utah.edu> wrote:
> I don't think there's a good way to write type assertions as the > moment, so let's add one. What syntax do you suggest? The simplest would just be a has-type that looks like an application. (define (id x) (has-type number x)) Actually, this one looks fine, too: (define (id x) (has-type x : number)) Thoughts? John > > At Mon, 6 Jan 2014 11:53:54 -0800, John Clements wrote: >> I’ve bitten the bullet and announced to my PL class that we’ll be using >> #lang >> plai-typed. Right now, I’m trying to figure out if there’s an easy way to do >> type debugging; in particular, I anticipate wanting to make assertions about >> the type of expressions that are buried inside of other expressions. Is >> there a >> form that allows me to do this? I had imagined that I could do it with >> ‘let’, >> but ‘let’ doesn’t take any type annotations. >> >> Currently, the best I’ve got is an in-line application to an identity >> function >> with a type attached. So, for instance, if I have this function >> >> (define (id x) >> x) >> >> … and I want to ensure that the expression ‘x’ has type number, I can write: >> >> >> (define (id x) >> ((lambda ((z : number)) z) x)) >> >> … but that’s pretty painful. Is there an easier way? (Yes, I could add a >> type >> annotation to the declaration of ‘x’ and to the return type of the function, >> but I’m imagining a larger function where the expression in question is >> neither >> an argument to nor the result of the function.) >> >> Many thanks, >> >> John >> >> >> >> >> ____________________ >> Racket Users list: >> http://lists.racket-lang.org/users ____________________ Racket Users list: http://lists.racket-lang.org/users
