Re: The cake's problem, dotty design and the approach to modularity.

On Monday, August 24, 2015 at 4:06:03 AM UTC+8, Simon Schäfer wrote:
>
>
>
> On 08/23/2015 09:05 PM, Shelby wrote:
>
> One issue I see with obligatory (versus optional) named parameters, is I 
> really wish Scala could do OCaml's (tuple and any other unapply) 
> destructing on the function parameters:
>
> # let distance (x1,y1) (x2,y2) =
>     sqrt ((x1 -. x2) ** 2. +. (y1 -. y2) ** 2.)
>
> So in Scala:
>
> def distance((x1,y1), (x2,y2)) = ...
>
> And why can't Scala infer those types given sqrt inputs Float? One of the big complaints I hear is Scala can't infer types.
>
>
> This is a complaint mostly by Haskell people or people doing lots of 
> functional programming in general. Beside from a few cases I don't see this 
> as very important. You don't want to have inferred argument types in public 
> methods for any nontrivial project.
>


Actually I agree on public methods exposed outside the "module". And to 
document your APIs as well. But afaik there are cases of 'public' methods 
not exposed to the public and more emphatically many cases of local 
functions where you don't want to write all that noisy boilerplate.

 

>
>
>
> Or at least why do I have to redeclare the types in a class that implements a trait where the types where already declared in the trait and there is no ambiguity?
>
> You don't have to:
>
> % s -Yinfer-argument-types
> Welcome to Scala version 2.11.7 (OpenJDK 64-Bit Server VM, Java 1.7.0_85).
> Type in expressions to have them evaluated.
> Type :help for more information.
>
> scala> trait T { def f(i: Int) = i }
> defined trait T
>
> scala> trait TT extends T { override def f(i) = i }
> defined trait TT
>

Well I thought I had tried in the past and received an error. I don't have 
a Scala installation on this computer (I'm at a different location) so I 
tried to access SimplyScala but it is down. On scala-js-fiddle.com your 
code does not compile unless I declare the type of the i parameter.

Naughty you using a subclassing example when you didn't need to make your 
point ;)

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