Unofficial bindings for GRIB API https://github.com/mjakob/hgrib

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GPL-3 licensed by Mattias Jakobsson
Maintained by mjakob422@gmail.com


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Unofficial bindings for ECMWF's GRIB API library for reading and writing WMO FM-92 GRIB edition 1 and edition 2 messages.

In this version of HGrib, a read-only monadic Haskell interface to GRIB API is provided. Raw bindings for the documented parts of GRIB API are also available. Future versions are intended to expand the higher-level Haskell interface to include, among other things, write support.


The following prerequisites are needed to build HGrib:

  • GRIB API >= 1.12 installed and discoverable by ghc (use cabal's --extra-include-dirs and --extra-lib-dirs if it's installed at a custom location); and

  • Haskell base >= 4.5; and

  • c2hs == 0.26.*.

With these requirements available, HGrib can be installed from Hackage with Cabal:

cabal install hgrib


HGrib provides a high-level monadic Haskell interface to GRIB API in Data.Grib. An example of its usage is GRIB API's get.c example re-written with HGrib:

import Control.Exception ( assert )
import Data.Grib
import Text.Printf       ( printf )

main :: IO ()
main = let filename = "test/stage/regular_latlon_surface.grib1" in
  runGribIO_ filename $ do
    setString "file" filename

    getLong "Ni" >>= liftIO . printf "numberOfPointsAlongAParallel=%d\n"
    getLong "Nj" >>= liftIO . printf "numberOfPointsAlongAMeridian=%d\n"

    getDouble "yFirst" >>=
      liftIO . printf "latitudeOfFirstGridPointInDegrees=%g\n"
    getDouble "xFirst" >>=
      liftIO . printf "longitudeOfFirstGridPointInDegrees=%g\n"
    getDouble "yLast"  >>=
      liftIO . printf "latitudeOfLastGridPointInDegrees=%g\n"
    getDouble "xLast"  >>=
      liftIO . printf "longitudeOfLastGridPointInDegrees=%g\n"
    getDouble "DyInDegrees" >>=
      liftIO . printf "jDirectionIncrementInDegrees=%g\n"
    getDouble "DxInDegrees" >>=
      liftIO . printf "iDirectionIncrementInDegrees=%g\n"

    getString "packingType" >>= liftIO . printf "packingType=%s\n"

    values <- getValues
    let numValues = length values
        average   = sum values / fromIntegral numValues
    liftIO $ printf "There are %d values, average is %g\n" numValues average

    filename' <- getString "file"
    liftIO $ assert (filename' == filename) (return ())

Raw bindings for the documented part of GRIB API is also available in Data.Grib.Raw. To be able to work with these bindings, bindings for C's fopen is provided in Data.Grib.Raw.CFile (which is re-exported by Data.Grib.Raw).

For more information, see HGrib's [reference documentation][HGrib Docs] generated by Haddock.


Issues, feature and pull requests are most welcome! In particular, please give suggestions on what you would like to see in the higher-level interface and let me know if there is any undocumented part of GRIB API that you would like to have included.


HGrib was created and is currently maintained by Mattias Jakobsson. It is released under the GNU General Public License v3.0. ECMWF's GRIB API is released under the Apache license. HGrib is in no way associated with ECMWF or the original library.


HGrib Change Log

  • Added skipMessage, skipMessageIf, and skipMessageIf_ to Data.Grib, three functions to easily skip unwanted GRIB messages in a file.

  • Added a GribIO monad in Data.Grib, which is a higher-level abstraction for reading GRIB files over the raw bindings in Data.Grib.Raw.

  • Moved Data.Grib.Raw.Exception up to Data.Grib.

  • Data.Grib.Raw no longer re-exports the Exception module mentioned above.

  • Made gribHandleNewFromFile return a Maybe GribHandle instead of a plain GribHandle. Nothing is returned if no more messages could be read from the given stream.

  • Re-organized the test utility modules.

  • Moved Data.Grib.Raw.Marshal from other to exposed modules, but it should still be considered an internal module and it is not included in the documentation.

  • Extended the compatible version range of GRIB API and the Haskell base library.

  • Added a gribGetApiVersion function to Data.Grib.Raw.

  • Included the Data.Grib.Raw.Exception module in Data.Grib.Raw and removed the marshal function withGribMultiHandle.

  • Removed

    • gribContextSetMemoryProc
    • gribContextSetPersistentMemoryProc
    • gribContextSetBufferMemoryProc
    • gribContextSetPrintingProc
    • gribContextSetLoggingProc

    and corresponding foreign function type definitions from Data.Grib.Raw to be able to mark all remaining functions unsafe from a FFI perspective.

  • Marked all foreign imports unsafe.

  • Integrated the source code repository with Travis CI.

  • Abandoned the plans to include the full GRIB API in grib_api.h (but requests to include specific parts are welcome).

  • Initial release.

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