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Record Types

• Example:
  • type ARec = {a: Int, b: Bool}
    value r: ARec = {a = 3, b = true}
    r.b
• Functions as components:
  • type FunRec = {f1: Int -> Int, f2: Real -> Real}
    value funRec: FunRec = {f1 = succ, f2 = sin}
• Concatenation of record types:
  • type NewRec = FunRec & {f3: Bool -> Bool}
• Private data structures:
  • value counter =
       let count = ref(0) in
       { inc = fun(n:Int) count := count+n
          total = fun() count
       }
  • counter.inc(3), counter.total()