hash() for floats

lib/pure/hashes.nim

@@ -122,3 +122,7 @@ proc hash*[T: tuple](x: T): THash =
     result = result !& hash(f)
   result = !$result
 
+proc hash*(x: float): THash {.inline.} =
+  var y = x + 1.0
+  result = cast[ptr THash](addr(y))[]
+

tests/run/thashes.nim

@@ -0,0 +1,7 @@
+import unittest
+import hashes
+
+suite "hashes":
+  suite "hashing":
+    test "0.0 and -0.0 should have the same hash value":
+      check hash(0.0) == hash(-0.0)