How can I run my haskell functions through Java

Question

Lets say I have a haskell function add in math.hs

How can I run the add function through a Java program and store the output as a variable?

Maybe something like the following:

public int runHaskell(String haskellFile) {
    int output;
    //run add function from file 'math.hs' and store result to output
    return output;
}

( If required I also have access to the object file: math.o and the interpreter file math.hi as well as the executable main.exe. )

This might involve some clever tricks with JNI. I'm curious to see what the answer is. — templatetypedef
– templatetypedef, Commented Feb 14, 2011 at 3:32
@templatetypedef I don't see how this would be any different than using JNI with C (GHC can generate intermediate C code) — Rafe Kettler
– Rafe Kettler, Commented Feb 14, 2011 at 3:36
@Rafe Kettler- True, but the naming conventions required by JNI and the fact that all the arguments have to be specific types would probably require you to build a "trampoline" C library that would then get linked in with the Haskell code. — templatetypedef
– templatetypedef, Commented Feb 14, 2011 at 3:49
If you need just a small portion of Haskell code, you might consider translating it to Jaskell ( docs.codehaus.org/display/JASKELL/Home ) — Landei
– Landei, Commented Feb 14, 2011 at 7:45

Anon. · Accepted Answer · 2011-02-14 03:46:33Z

4

The easy (but clumsy) way:

Runtime.exec()

Then you can listen to the output of the Haskell program, and then parse it for the result.

Alternatively, you can write a small wrapper for JNI that calls directly into your Haskell stuff.

answered Feb 14, 2011 at 3:46

Anon.

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2 Comments

BinRoot Over a year ago

Hmm. How do I listen for the output after I use exec() on the executable haskell program?

Anon. Over a year ago

@Nick: exec returns a Process object, which you can use to get the stream that the process writes its output to.

Yasir Arsanukayev · Accepted Answer · 2011-02-14 05:24:40Z

1

You could use some of RPC frameworks, for example, Apache Thrift, which supports C++, Java, Python, PHP, Ruby, Erlang, Perl, Haskell, C#, Cocoa, Smalltalk, and OCaml.

There's also BERT-RPC client and server library for Haskell, but I'm not sure a Java port exists.

answered Feb 14, 2011 at 5:24

Yasir Arsanukayev

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Comments

Chris Dennett · Accepted Answer · 2011-02-14 05:27:11Z

1

This might help: http://www.haskell.org/haskellwiki/Applications_and_libraries/Interfacing_other_languages. There is also Jaskell which might be able to run your entire source code under the JVM, allowing you to easily interface.

answered Feb 14, 2011 at 5:27

Chris Dennett

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