regression/abstype.sml

   1 abstype t = T
   2 with
   3    val eq = op =
   4 end
   5 val _ = eq (3, 3)
   6
   7 abstype t = T
   8 with
   9    val t = T
  10    val eq = op =
  11 end
  12 val _ = eq (t, t)
  13
  14 abstype t = T
  15 with
  16    val t = T
  17    val eq = op =
  18    val _ = eq (t, t)
  19 end
  20 val _ = eq (2, 3)
  21
  22 abstype t = T
  23 with
  24    val t = T
  25    val eq = op =
  26    val _ = eq (t, t)
  27 end
  28 val _ = eq (t, t)
  29
  30 abstype t = T
  31 with
  32    val t = T
  33    val eq = op =
  34    val _ = eq (t, t) andalso eq (2, 3)
  35 end
  36 val _ = eq (2, 3)
  37
  38 (* with abstype *)
  39
  40 structure S =
  41   struct
  42     abstype s = S
  43     with
  44       val a = S
  45     end
  46   end
  47
  48 signature F =
  49   sig
  50     val b : S.s
  51   end
  52
  53 functor F() : F =
  54   struct
  55     type s = S.s
  56     val b = S.a
  57   end
  58
  59
  60 functor K() =
  61   struct
  62     structure F = F()
  63   end
  64
  65 structure K = K()
  66
  67 (* abstype.sml *)
  68
  69 (* Checks equality inferred for abstype environments. *)
  70
  71 abstype t = T with
  72     datatype u = U of t
  73     val eq = op=
  74 end
  75
  76 fun eq1(t1, t2) = U t1 = U t2;
  77 fun eq2(t1, t2 : t) = eq(t1, t2);