Question

I’m looking for a way to run an arbitrary Haskell code safely (or refuse to run unsafe code).

Must have:

• module/function whitelist
• timeout on execution
• memory usage restriction

Capabilities I would like to see:

• ability to kill thread
• compiling the modules to native code
• caching of compiled code
• running several interpreters concurrently
• complex datatype for compiler errors (insted of simple message in String)

With that sort of functionality it would be possible to implement a browser plugin capable of running arbitrary Haskell code, which is the idea I have in mind.

EDIT: I’ve got two answers, both great. Thanks! The sad part is that there doesn’t seem to be ready-to-go library, just a similar program. It’s a useful resource though. Anyway I think I’ll wait for 7.2.1 to be released and try to use SafeHaskell in my own program.

Answer 1

We’ve been doing this for about 8 years now in lambdabot, which supports:

• a controlled namespace
• OS-enforced timeouts
• native code modules
• caching
• concurrent interactive top-levels
• custom error message returns.

This series of rules is documented, see:

• Safely running untrusted Haskell code
• mueval, an alternative implementation based on ghc-api

The approach to safety taken in lambdabot inspired the Safe Haskell language extension work.

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For approaches to dynamic extension of compiled Haskell applications, in Haskell, see the two papers:

• Dynamic Extension of Typed Functional Languages, and
• Dynamic applications from the ground up.