Parser (streamed): fix default value for cell type

According to specification if cell has no `t` attribute,
it has a default value as `n` - number.

Author: NikitaRazmakhnin

data/floats.xlsx

@@ -688,7 +688,7 @@ parseStyle list =
 parseType :: SheetValues -> Either TypeError ExcelValueType
 parseType list =
   case findName "t" list of
-    Nothing -> pure Untyped
+    Nothing -> Right TN -- according to spec by default if `t` is missing then default value is `n` - number
     Just (_nm, valText)->
       case valText of
         "n"         -> Right TN

src/Codec/Xlsx/Parser/Stream.hs

@@ -90,6 +90,10 @@ tests =
 
       testGroup "Reader/inline strings"
       [ testCase "Can parse row with inline strings" inlineStringsAreParsed
+      ],
+
+      testGroup "Reader/floats parsing"
+      [ testCase "Can parse untyped values as floats" untypedCellsAreParsedAsFloats
       ]
     ]
 
@@ -205,4 +209,23 @@ inlineStringsAreParsed = do
         ]
   expected @==? (items ^.. traversed . si_row . ri_cell_row)
 
+untypedCellsAreParsedAsFloats :: IO ()
+untypedCellsAreParsedAsFloats = do
+  -- values in that file are under `General` cell-type and are not marked
+  -- as numbers explicitly in `t` attribute.
+  items <- runXlsxM "data/floats.xlsx" $ collectItems $ makeIndex 1
+  let defCell v = def
+        { _cellValue = Just v
+        }
+      expected =
+        [ IM.fromList [ (1, def & cellValue ?~ CellDouble 12.0) ]
+        , IM.fromList [ (1, def & cellValue ?~ CellDouble 13.0) ]
+        -- cell below has explicit `Numeric` type, while others are all `General`,
+        -- but sometimes excel does not add a `t="n"` attr even to numeric cells
+        -- but it should be default as number in any cases if `t` is missing
+        , IM.fromList [ (1, def & cellValue ?~ CellDouble 14.0 & cellStyle ?~ 1 ) ]
+        , IM.fromList [ (1, def & cellValue ?~ CellDouble 15.0) ]
+        ]
+  expected @==? (_ri_cell_row . _si_row <$> items)
+
 #endif