Re: [Haskell-cafe] newbie - how to call a Haskell interpreter from C

On Sat, Aug 25, 2007 at 12:34:45PM -0400, Brock Peabody wrote:

On 8/25/07, Henk-Jan van Tuyl wrote:

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The easiest way to run Haskell software from a C program is to give the shell command: runhaskell Foo.hs

I'm a newbie but not that new :) I really have to be able to interpret the Haskell from within the same process.

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A more advanced way is, to link Haskell libraries by means of the foreign function interface (FFI) [1]. There are several tools to support FFI development [2]. I am sure my list of URL's is not complete.

[1] http://www.cse.unsw.edu.au/~chak/haskell/ffi/ http://www.cse.unsw.edu.au/%7Echak/haskell/ffi/ http://www.haskell.org/haskellwiki/FFI_Introduction http://www.haskell.org/haskellwiki/FFI_cook_book

[2] http://www.haskell.org/haskellwiki/FFI_imports_packaging_utility http://www.haskell.org/haskellwiki/HSFFIG

My understanding is that FFI helps you to call into other languages from Haskell and vice-versa. I will definitely need this, but what I can't figure out how to do is to invoke the ghci or hugs interpreter programmatically, in-process. I didn't see a way to do that in the links you listed, am I missing something?

No, you're not missing anything, and there are no deliberately embeddable Haskell interpreters. Your options are: 1a. GHC, native code: Link libHSplugins.a into your program (compile Don's hs-plugins library). Then call the external functions described in http://www.cse.unsw.edu.au/~dons/hs-plugins/hs-plugins-Z-H-4.html#node_sec_7..., Pro: Full GHC runtime speed Con: Full GHC compile-time sloth As big as GHC (20mbytes file size) Leaks memory 1b. GHC, bytecode: Write a binding to the GHC-API runStmt function. foreign export it. Pro: As fast as GHCi No leaks Con: Still huge Slow runtime 2. Hugs Link Hugs. Study the source code to runhugs. Pro: Much faster loading Much smaller footprint Con: Less polished Slow runtime Stefan