Issue #181: Initial Parquet Writer Skeleton and WSL Build Verification

cabal.project

@@ -1,3 +1 @@
-packages:
-    .
-    dataframe-fastcsv
+packages: .

dataframe.cabal

@@ -46,7 +46,8 @@ common warnings
 library
     import: warnings
     default-extensions: Strict
-    exposed-modules: DataFrame,
+    exposed-modules:
+                    DataFrame,
                     DataFrame.Lazy,
                     DataFrame.Functions,
                     DataFrame.Synthesis,
@@ -111,7 +112,8 @@ library
                     DataFrame.Typed.TH,
                     DataFrame.Typed.Expr,
                     DataFrame.Typed.Lazy,
-                    DataFrame.Typed
+                    DataFrame.Typed,
+                    DataFrame.IO.Parquet.Writer
     build-depends:    base >= 4 && <5,
                       deepseq >= 1 && < 2,
                       aeson >= 0.11.0.0 && < 3,

src/DataFrame/IO/Parquet/Writer.hs

@@ -0,0 +1,18 @@
+module DataFrame.IO.Parquet.Writer (writeParquet) where
+
+import qualified Data.ByteString.Builder as B
+import System.IO (IOMode(WriteMode), withBinaryFile)
+
+-- Using the path we found with grep
+import DataFrame.Internal.DataFrame (DataFrame)
+
+-- | Minimalist implementation to verify the build system works
+writeParquet :: FilePath -> DataFrame -> IO ()
+writeParquet path _df = do
+    withBinaryFile path WriteMode $ \handle -> do
+        -- Every Parquet file MUST start and end with these 4 bytes
+        B.hPutBuilder handle (B.string8 "PAR1")
+
+        -- (Logic for RowGroups will go here later)
+
+        B.hPutBuilder handle (B.string8 "PAR1")