Make NaN equal NaN

src/preserves/private/values.nim

@@ -1,7 +1,7 @@
 # SPDX-FileCopyrightText: ☭ Emery Hemingway
 # SPDX-License-Identifier: Unlicense
 
-import std/[hashes, options, sets, sequtils, tables]
+import std/[hashes, math, options, sets, sequtils, tables]
 
 import bigints
 
@@ -56,6 +56,11 @@ type
 
   DictEntry*[E] = tuple[key: Preserve[E], val: Preserve[E]]
 
+func `===`[T: SomeFloat](a, b: T): bool =
+  ## Compare where Nan == NaN.
+  let class = a.classify
+  (class == b.classify) and ((class notin {fcNormal,fcSubnormal}) or (a == b))
+
 func `==`*[A, B](x: Preserve[A]; y: Preserve[B]): bool =
   ## Check `x` and `y` for equivalence.
   if x.kind == y.kind and x.embedded == y.embedded:
@@ -63,9 +68,9 @@ func `==`*[A, B](x: Preserve[A]; y: Preserve[B]): bool =
     of pkBoolean:
       result = x.bool == y.bool
     of pkFloat:
-      result = x.float == y.float
+      result = x.float === y.float
     of pkDouble:
-      result = x.double == y.double
+      result = x.double === y.double
     of pkRegister:
       result = x.register == y.register
     of pkBigInt: