ADTs in Typed Racket with macros

Немного изящного (макроебства)[http://lexi-lambda.github.io/blog/2015/12/21/adts-in-typed-racket-with-macros/] и в тайпед/ракетке можно юзать ADT с паттерн матчингом.
(Прямо как во взрослых крутых языках).

(define-datatype Expr
  (Value Number)
  (Add Expr Expr)
  (Subtract Expr Expr)
  (Multiply Expr Expr)
  (Divide Expr Expr))

(: evaluate (Expr -> Number))
(define (evaluate e)
  (match e
    [(Value x)      x                            ]
    [(Add a b)      (+ (evaluate a) (evaluate b))]
    [(Subtract a b) (- (evaluate a) (evaluate b))]
    [(Multiply a b) (* (evaluate a) (evaluate b))]
    [(Divide a b)   (/ (evaluate a) (evaluate b))]))

> (evaluate (Add (Value 1)

                 (Multiply (Divide (Value 1) (Value 2))
                           (Value 7))))
4 1/2

Интересно, ебанется ли кто-нить достаточно чтобы набыдлить какой-нить аналог хаскеля или scalaz?

the Strict language extension*

Add a new language extension -XStrict which turns all bindings strict
as if the programmer had written a ! before it. This also upgrades
ordinary Haskell to allow recursive and polymorphic strict bindings.

https://github.com/ghc/ghc/commit/46a03fbec6a02761db079d1746532565f34c340f

Все теперь можно думать о том, чтобы учить хаскель. // Ну или Ocaml

Кстати, спалите haskell vs ocaml в вопросах:
* C-FFI
* многопоточности
* ease of deployment
* поддержки ARM
* легкости получения soft realtime

Олсо, кто-нить объекты в Ocaml юзает или это шутка?
Наткнулся на такой комент на HN:
/However, with a few minor tweaks (e.g. an option type), I would rather have the C# type inference than the OCaml one. The reason is that, if I want to do something very clever, I will not find myself limited to code that I can actually prove to the OCaml compiler as correct: I have, time and time again, resorted to reflection and code generation to work around such situations. In other words C#'s Obj.magic is a lot more powerful (and safe, and expressive) than OCaml's.

A fairly good example is Eliom's way of expressing the parameters of a service. In C# you would write in a PageController class

public Details Update(PageId id, UserId user, [PostBody] Details body) 

and have your web framework automatically bind this to POST /page/update/{id}?user={user} with the appropriate serialization for PageId and UserId. And writing such a framework is easy: a couple hundred lines of code, with run-time type safety.

In OCaml you have to understand the entire Eliom_parameter framework: https://ocsigen.org/eliom/4.2/api/server/Eliom_parameter Just think of the mental firepower needed to create that framework in the first place!/