types.txt

(declare [X :type Bool])

(declare [x :type Char])

(declare [x :type Int])
(declare [y :type Word])

(declare [x :type Rational])
(declare [y :type String])

(declare [x :type [Int]])

(declare [x :type (Int Int) -> (Int)])

-----------ploymorphic function------------
-----------ploymorphic
(define fst
  (fun ([a b] [-> a.type])))

-----------subtype-----------------
(define fst
  (fun ([:a (Int (a < 2))])))
------------constrained
(typename (:T Floadable))
(define length
  (fun ([:a T] [-> T])))

(define head
  (fun ([array] [-> array.type])))

(typename (:T Num))
(define add
  (fun ([:x T] [-> T])
    (+ x 1)))

(add :x 1.0)
(add :x 1.2)
(add :x 1.3)
(add :y 1.0)

----------type synonym-----------------
(type RGB [Int Int Int])
(type ID Int)
(type BookName String)


(typename (:a Eq))
(define add
  (fun ([:b Int] [-> Int])))

---what is the a?--------------
(Class Eq a
  [== :type [(a a) -> Bool]]
  [/= :type [(a a) -> Bool]])
  
---curry function----------------
(define add
  (fun ([:a Int] [:b Int] [-> (Int -> Int)])
    (fun (c)
      (+ a (+ b c)))))