Added. At Mon, 6 Jan 2014 12:04:16 -0800, John Clements wrote: > > 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
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