add bytes, bytearray, and pasteIO

src/Data/ByteArray/Builder/Small.hs

@@ -12,17 +12,22 @@ module Data.ByteArray.Builder.Small
     -- * Evaluation
   , run
   , pasteST
+  , pasteIO
+    -- * Materialized Byte Sequences
+  , bytes
+  , bytearray
     -- * Numbers
   , word64Dec
   ) where
 
 import Control.Monad.Primitive
+import Control.Monad.ST
+import Data.Bytes.Types
 import Data.Char (ord)
 import Data.Primitive
 import GHC.Exts
-import GHC.Word
-import Data.Bytes.Types
 import GHC.ST
+import GHC.Word
 
 -- | An unmaterialized sequence of bytes that may be pasted
 -- into a mutable byte array.
@@ -59,6 +64,10 @@ pasteST (Builder f) (MutableBytes (MutableByteArray arr) (I# off) (I# len)) =
       then (# s1, Just (I# r) #)
       else (# s1, Nothing #)
 
+pasteIO :: Builder -> MutableBytes RealWorld -> IO (Maybe Int)
+{-# inline pasteIO #-}
+pasteIO b m = stToIO (pasteST b m)
+
 construct :: (forall s. MutableBytes s -> ST s (Maybe Int)) -> Builder
 construct f = Builder
   $ \arr off len s0 ->
@@ -67,6 +76,16 @@ construct f = Builder
         Nothing -> (# s1, (-1#) #)
         Just (I# n) -> (# s1, n #)
 
+bytearray :: ByteArray -> Builder
+bytearray a = bytes (Bytes a 0 (sizeofByteArray a))
+
+bytes :: Bytes -> Builder
+bytes (Bytes src soff slen) = construct $ \(MutableBytes arr off len) -> if len >= slen
+  then do
+    copyByteArray arr off src soff slen
+    pure (Just (len - slen))
+  else pure Nothing
+
 word64Dec :: Word64 -> Builder
 word64Dec (W64# w) = word64Dec# w