Merge pull request #1005 from hylo-lang/min-max-int

Library/Hylo/Core/Comparable.hylo

@@ -20,3 +20,13 @@ extension Comparable {
   fun infix>= (_ other: Self) -> Bool { !(self < other) }
 
 }
+
+/// Returns the lesser of `x` and `y`.
+public subscript min<T: Comparable>(_ x: T, _ y: T): T {
+  if y < x { yield y } else { yield x }
+}
+
+/// Returns the greater of `x` and `y`.
+public subscript max<T: Comparable>(_ x: T, _ y: T): T {
+  if x < y { yield y } else { yield x }
+}

Library/Hylo/Core/Int.hylo

@@ -219,6 +219,8 @@ public conformance Int: Copyable {
 
 }
 
+public conformance Int: Comparable {}
+
 public conformance Int: ForeignConvertible {
 
   public typealias ForeignRepresentation = Builtin.word

Tests/LibraryTests/TestCases/IntTests.hylo

@@ -1,6 +1,21 @@
 //- compileAndRun expecting: success
 
+fun test_min() {
+  precondition(min[1, 2] == 1)
+  precondition(min[1, 1] == 1)
+  precondition(min[2, 1] == 1)
+}
+
+fun test_max() {
+  precondition(max[1, 2] == 2)
+  precondition(max[1, 1] == 1)
+  precondition(max[2, 1] == 2)
+}
+
 public fun main() {
   // Int.init()
   precondition(Int() == 0)
+
+  test_min()
+  test_max()
 }