pony-tutorial VS effekt

I don't think that there is a book written about Pony, but the tutorial and the list of patterns (WIP) are all you need to learn the language.

[Pony](https://tutorial.ponylang.io/): actors, reference capabilities, object capabilities.

Pony is a relatively young but interesting language with capabilities-security.

Well, depends on how you define ownership. Pony 's type system has reference capabilities which let you define who's allowed to do what to a reference and part of it sort of deals with ownership (along the lines of "this actor is allowed to do Y to the reference, other actors are allowed to do Z"). You can eg. have methods that return an isolated value that guarantees that there are no other references to that value, meaning it's automatically thread safe. You can also define things as vals which says that they are globally immutable, refs which give the current actor read/write capabilities but can't be shared with other actors

The alternatives are:

- Division must be impure (because it can throw an exception)

- Division must be partial - i.e. return Option[Int].

Both seem worse compared to defining division by zero as zero. Coq, Lean, and Pony do the same. https://github.com/ponylang/pony-tutorial/blob/master/conten...

I like it. Modern languages that distinguish between pure and impure programs like Flix, Koka, and Effekt do so on the type level instead of syntactically. This has three advantages:

The problem with checked exceptions been identified and solved. The same problem and solution applies to effect handlers. Effekt is a language with lexical effect handlers which doesn't have this problem. Consider the following program in Effekt:

Yes, for you this is the right decision. But for us going to CPS makes everything significantly easier and in cases where you do use control effects significantly faster. For our language Effekt we are exploring different tradeoffs in different backends.

This pattern they observe is nicely captured by effect handlers. These examples are written in Effekt.

This is beyond my level of expertise. But effect tracking? There are some cool languages out there that do that consistently! Search for "algebraic effects". My favorite is Koka. Effekt also seems to be a popular choice.

https://effekt-lang.org/ A research language with effect handlers and lightweight effect polymorphism

Examples are languages like Koka, Effekt, Links, or Unison. These languages come with a type-and-effect system: a function's type not only tell you which values the function accepts and which values it returns, but also which effects it has. This is relevant to your question, because throwing an exception is one such effect.

It seems that with Effekt we are pursuing the same goal, but coming from the opposite direction, perhaps one day we will meet in the middle :). We start from a purely functional language and carefully add effects like mutation.

- https://effekt-lang.org/