Re: Re: Scala - a Roadmap

Thank you. I do not understand what the syntax "functor =>" means in that 
context?

Also how can abstract type members express Liskov Substitution Principle 
variance?

http://stackoverflow.com/questions/5351248/type-members-and-covariance

On Monday, June 15, 2015 at 3:25:08 PM UTC+8, martin wrote:
>
> That would lose information. I believe you have to write it like this: 
>
> trait Functor { functor => 
>   type T 
>   type Subtype <: Functor { type T = functor.T } 
>   def map[R] : (T => R) => Subtype { type T = R } 
> } 
>
> To avoid misunderstanding (because I found many people do 
> misunderstand this point): That would be a compiler expansion; you 
> will usually still write the original parameterized version: 
>
> > trait Functor[T, Subtype[T] <: Functor[T, Subtype[T]] { 
> >   def map : (T => R) => Subtype[R] 
> > } 
> > 
>
> Cheers 
>
>  - Martin 
>

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