Add 'IsSize' instance for 'Word'

This resolves issue #33

Author: nc6

src/Codec/CBOR/Cuddle/Huddle.hs

@@ -431,6 +431,10 @@ class IsSize a where
   sizeAsCDDL :: a -> C.Type2
   sizeAsString :: a -> String
 
+instance IsSize Word where
+  sizeAsCDDL = C.T2Value . C.VUInt . fromIntegral
+  sizeAsString = show 
+
 instance IsSize Word64 where
   sizeAsCDDL = C.T2Value . C.VUInt
   sizeAsString = show

test/Test/Codec/CBOR/Cuddle/Huddle.hs

@@ -22,6 +22,7 @@ huddleSpec = describe "huddle" $ do
   mapSpec
   nestedSpec
   genericSpec
+  constraintSpec
 
 basicAssign :: Spec
 basicAssign = describe "basic assignment" $ do
@@ -111,6 +112,12 @@ genericSpec =
             toSortedCDDL (collectFrom ["mymap" =:= dict VUInt VText])
               `shouldMatchParseCDDL` "dict<a0, b0> = {* a0 => b0}\n mymap = dict<uint, text>"
 
+constraintSpec :: Spec 
+constraintSpec = 
+  describe "Constraints" $ 
+    it "Size can take a Word" $ 
+      toSortedCDDL (collectFrom ["sz" =:= VUInt `sized` (2 :: Word)])
+        `shouldMatchParseCDDL` "sz = uint .size 2"
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 -- Helper functions
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