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This repository contains the source for the haskell Official Repository on DockerHub.

Haskell is a lazy, functional, statically-typed programming language with advanced type system features such as higher-rank, higher-kinded parametric polymorphism, monadic effects, generalized algebraic data types (GADTs), flexible type classes, associated type families, and more.

Haskell's ghc is a portable, optimizing compiler with a foreign-function interface (FFI), an LLVM backend, and sophisticated runtime support for concurrency, explicit/implicit parallelism, runtime profiling, etc. Other Haskell tools like criterion, quickcheck, hpc, and haddock provide advanced benchmarking, property-based testing, code coverage, and documentation generation.

A large number of production-quality Haskell libraries are available from Hackage in the form of Cabal packages. The traditional cabal tool, or the more recent stack tool (available in 7.10.3+) can be used to streamline working with Cabal packages. The key differences are summarized here. New users are encouraged to start with stack.

About this image

This image ships a minimal Haskell toolchain with the following packages from the hvr PPA:

• ghc
• alex
• cabal-install
• happy

As of 7.10.3, the stack tool is included via FPComplete's Debian repository.

Note: The GHC developers do not support legacy release branches (i.e. 7.8.x). While older GHC release tags are available in this DockerHub repository, only the latest stable release (or upcoming release candidates) will be shown in the "Supported tags ..." section at the top of the DockerHub repository page.

How to use this image

Start an interactive interpreter session with ghci:

$ docker run -it --rm haskell:7.10.3
GHCi, version 7.10.3: http://www.haskell.org/ghc/  :? for help
Prelude>

Dockerize an application from Hackage with a Dockerfile:

FROM haskell:7
RUN stack install pandoc pandoc-citeproc
ENTRYPOINT ["pandoc"]

Alternatively, using cabal:

FROM haskell:7
RUN cabal update && cabal install pandoc pandoc-citeproc
ENTRYPOINT ["pandoc"]

Iteratively develop a Haskell application with a Dockerfile utilizing the build cache:

FROM haskell:7.10

WORKDIR /opt/server

RUN cabal update

# Add just the .cabal file to capture dependencies
COPY ./snap-example.cabal /opt/server/snap-example.cabal

# Docker will cache this command as a layer, freeing us up to
# modify source code without re-installing dependencies
# (unless the .cabal file changes!)
RUN cabal install --only-dependencies -j4

# Add and Install Application Code
COPY . /opt/server
RUN cabal install

CMD ["snap-example"]

Examples

See the application snippet above in more detail in the example snap application.

Issues and Contributing

If you have any problems with or questions about this image, please contact us through a GitHub issue.

You can also reach many of the official image maintainers via the #docker-library IRC channel on Freenode.

You are invited to contribute new features, fixes, or updates directly via pull requests on GitHub.