When someone defines a universal type ∀X they’re saying: You can plug in whatever type you want, I don’t need to know anything about the type to do my job, I’ll only refer to it opaquely as X. When someone defines an existential type ∃X they’re saying: I’ll use whatever type I want here; you … Read more
To explain it, we first have to explain nested classes in Scala. Consider this simple example: class A { class B def f(b: B) = println(“Got my B!”) } Now let’s try something with it: scala> val a1 = new A a1: A = A@2fa8ecf4 scala> val a2 = new A a2: A = A@4bed4c8 … Read more
The ability of the interpreter to deduce type and type conversions makes development time faster, but it also can provoke runtime failures which you just cannot get in a statically typed language where you catch them at compile time. But which one’s better (or even if that’s always true) is hotly discussed in the community … Read more