[MLton-user] Extended Basis Library: Partial order concept

[Geoffrey Alan Washburn]

    I just spent a couple minutes fiddling with a revision to the 
ORDERED concept to introduce partial orders.  I do not really care for 
the names I am using here, but I was not sure whether it would be 
desirable to have types and signatures with names as long as 
»partially_ordered« or »TOTALLY_ORDERED_EX«.

Index: ../ext-basis/public/concept/ordered.sig
===================================================================
--- ../ext-basis/public/concept/ordered.sig     (revision 5543)
+++ ../ext-basis/public/concept/ordered.sig     (working copy)
@@ -21,29 +21,47 @@
     *)
 end

-signature ORDERED_EX = sig
-   type ordered_ex
+(** == POrdered ==
+ *
+ * A pordered type implements a partial order.
+ *)

-   val < : ordered_ex BinPr.t
-   (** {i < j} returns {true} iff {i} is less than {j}. *)
+signature PORDERED_CORE = sig
+   type pordered

-   val <= : ordered_ex BinPr.t
+   val <= : pordered BinPr.t
    (** {i <= j} returns {true} iff {i} is less than or equal to {j}. *)
+end

-   val > : ordered_ex BinPr.t
+signature PORDERED_EX = sig
+   type pordered_ex
+
+   val < : pordered_ex BinPr.t
+   (** {i < j} returns {true} iff {i} is less than {j}. *)
+
+   val > : pordered_ex BinPr.t
    (** {i > j} returns {true} iff {i} is greater than {j}. *)

-   val >= : ordered_ex BinPr.t
+   val >= : pordered_ex BinPr.t
    (** {i >= j} returns {true} iff {i} is greater than or equal to {j}. *)
+end

-   val max : ordered_ex BinOp.t
+signature TORDERED_EX = sig
+   type tordered_ex
+
+   val max : tordered_ex BinOp.t
    (** Returns the larger of the arguments. *)

-   val min : ordered_ex BinOp.t
+   val min : tordered_ex BinOp.t
    (** Returns the smaller of the arguments. *)
 end

 signature ORDERED = sig
-   include ORDERED_CORE EQUALITY ORDERED_EX
-   sharing type ordered = equality = ordered_ex
+   include ORDERED_CORE PORDERED_CORE EQUALITY PORDERED_EX TORDERED_EX
+   sharing type ordered = pordered = equality = pordered_ex = tordered_ex
 end
+
+signature PORDERED = sig
+   include PORDERED_CORE EQUALITY PORDERED_EX
+   sharing type pordered = equality = pordered_ex
+end


-- 
[Geoff Washburn|geoffw at cis.upenn.edu|http://www.cis.upenn.edu/~geoffw/]

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