以下是代码:
在代码文件
getSpareBuffer :: Handle__ -> IO (BufferMode, CharBuffer)
getSpareBuffer Handle__{haCharBuffer=ref,
haBuffers=spare_ref,
haBufferMode=mode}
= do
case mode of
NoBuffering -> return (mode, error "no buffer!")
_ -> do
bufs <- readIORef spare_ref
buf <- readIORef ref
case bufs of
BufferListCons b rest -> do
writeIORef spare_ref rest
return ( mode, emptyBuffer b (bufSize buf) WriteBuffer)
BufferListNil -> do
new_buf <- newCharBuffer (bufSize buf) WriteBuffer
return (mode, new_buf)
这段代码来自GHC源代码 (ghc-7.4.1\libraries\base\GHC\IO\Handle\Text.hs)。我想知道为什么代码在参数的位置使用花括号,以及变量haCharBuffer,haBuffers,haBufferMode
如何从ref, spare_ref
和mode
中获取值。这些值还没有定义。
GHC的另一段代码需要澄清:
flushByteWriteBuffer :: Handle__ -> IO ()
flushByteWriteBuffer h_@Handle__{..} = do
bbuf <- readIORef haByteBuffer
when (not (isEmptyBuffer bbuf)) $ do
bbuf' <- Buffered.flushWriteBuffer haDevice bbuf
writeIORef haByteBuffer bbuf'
在代码文件
ghc-7.4.1\libraries\base\GHC\IO\Handle\Internals.hs
中,大括号内使用点号 ({..}
) 的含义是什么?