[racket] Typed Racket vs. Haskell

Technically this should be possible and conceptually preferable. 

However, it does come with redundancies that conventional type annotations avoid and I am not sure how much of this redundancy we should push on programmers. 


On Sep 20, 2012, at 4:51 PM, Patrick Mahoney wrote:

> Hey all, 
> 
> One feature of typed racket that makes translation between untyped and typed code somewhat less simple than adding or removing type signatures is that certain forms require rewriting/alteration of the untyped form itself. Others allow stand-alone declaration of the types prior to the form. 
> 
>   #lang racket
> (define (louder s) (string-append s "!"))
> 
> becomes 
> #lang typed/racket 
> (: louder : String -> String)
> (define (louder s) (string-append s "!"))
> 
> but 
> 
> #lang racket
> (struct arrow (dom cod))
> 
> becomes 
> #lang typed/racket
> (struct: arrow ([dom : Any] [cod : Any]))
> 
> or a stricter
> #lang typed/racket
> (struct: (A B) arrow ([dom : A] [cod : B]))
> 
> I tend to prefer the former case, as moving to untyped code just requires removal of the (: louder ...) type declaration. 
> 
> I'd really dig the addition of an alternate way to declare types on structs in particular: 
> 
> #lang typed/racket
> (: arrow (ForAll (A B) (StructOf A B)))
> (struct arrow (a b))
> 
> This allows me to reuse my mental untyped code parser for struct forms, while the struct: form requires an additional rule. It also makes declaration of types more uniform. Not sure whether this is possible. 
> 
> Thanks all, 
> -Patrick
> 
> On 20 September 2012 12:02, <thorsopia at lavabit.com> wrote:
> Thank you all for the replies.
> 
> I'll give it a try.
> 
> 
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