read is:exact package:base set:included-with-ghc

read :: Read a => String -> a
base Prelude Text.Read
The read function reads input from a string, which must be completely consumed by the input process. read fails with an error if the parse is unsuccessful, and it is therefore discouraged from being used in real applications. Use readMaybe or readEither for safe alternatives. 
>>> read "123" :: Int
123

>>> read "hello" :: Int
*** Exception: Prelude.read: no parse
read :: RawIO a => a -> Ptr Word8 -> Word64 -> Int -> IO Int
base GHC.IO.Device
Read up to the specified number of bytes starting from a specified offset, returning the number of bytes actually read. This function should only block if there is no data available. If there is not enough data available, then the function should just return the available data. A return value of zero indicates that the end of the data stream (e.g. end of file) has been reached.