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Apache OpenDAL™ Haskell Binding

A Haskell binding for OpenDAL: access S3, GCS, Azure Blob, the local filesystem, and 50+ more services through one API, with the Rust core underneath.

New to the model behind the API? Read Concepts first — service, operator, layer, operation are the same four ideas in every language.

note

This binding has its own version number, independent of the Rust core. When checking for updates or compatibility, always refer to this binding's version rather than the core version.

Status​

Experimental / WIP. The binding is unreleased and not yet published to Hackage. The API may change without notice. Use it to experiment or contribute, but do not rely on it in production.

Capabilities​

  • Blocking IO — all operations run in IO; there is no async API yet.
  • OperatorT monad — compose operations with do-notation; errors surface as Left OpenDALError through ExceptT under the hood.
  • Raw IO functions — every operation is also available as a plain IO function returning Either OpenDALError a for direct use without the monad transformer.
  • Core operations — read, write, stat, delete, copy, rename, list (shallow and recursive scan), create directory, remove-all, writer (append and overwrite).
  • Logging — optional structured logging via co-log.
  • Services — whichever services the bundled Rust library is compiled with; the memory service works out of the box for testing.

Build​

The binding is not on Hackage; build from source inside bindings/haskell/:

# Build the Rust FFI layer and the Haskell library
cabal build

# Run the test suite
cabal test

# Generate Haddock documentation
cabal haddock

Requires a working Rust toolchain (cargo) in addition to GHC and cabal. The build has been tested with GHC 9.4.8.

Next steps​

  1. Getting started — build an operator, read and write, handle errors.