Data.Grib

The GRIB Monad

type GribIO = ReaderT GribEnv IO

The GribIO monad is a ReaderT monad transformer over the IO monad with a GribEnv environment.

runGribIO

Arguments

:: FilePath

a path to a GRIB file

-> GribIO a

an action to take on each GRIB message in the file

-> IO [a]

the results of the actions

Run an action on each GRIB message in a file and collect the results.

This operation may fail with:

• any IOError raised by openBinaryCFile;
• any GribError raised by gribHandleNewFromFile; or
• any other exception raised by the given GribIO action.

runGribIO_ :: FilePath -> GribIO a -> IO ()

Like runGribIO, but discard the results.

data GribEnv

The reader environment of GribIO containing the current filename, a GribHandle, and its index in the file.

Get values

These operations may fail with:

• isGribException GribNotFound if the key is missing.

getDouble :: Key -> GribIO Double

Get the value for a key as a float.

getLong :: Key -> GribIO Int

Get the value for a key as an integer.

getString :: Key -> GribIO String

Get the value for a key as a string.

getValues :: GribIO [Double]

Get the data values of the GRIB message as floats.

Set values

These operations may fail with:

• isGribException GribNotFound if the key is missing; or
• isGribException GribReadOnly if the key is read-only.

setDouble :: Key -> Double -> GribIO ()

Set the value of a key from a float.

setLong :: Key -> Int -> GribIO ()

Set the value of a key from an integer.

setString :: Key -> String -> GribIO ()

Set the value of a key from a string.

setValues :: [Double] -> GribIO ()

Set the values of the GRIB message from floats.

Utilities

getFilename :: GribIO FilePath

Return the name of the file being read.

getIndex :: GribIO Int

Return the zero-based index of the current message in the file.

getHandle :: GribIO GribHandle

Return the current GribHandle for use with the Raw GRIB API bindings.

liftIO :: MonadIO m => forall a. IO a -> m a

Lift a computation from the IO monad.