https://github.com/nh2/haskell-from-python
Example how to call Haskell from Python easily (using ctypes.cdll.LoadLibrary)
https://github.com/nh2/haskell-from-python
Last synced: 28 days ago
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Example how to call Haskell from Python easily (using ctypes.cdll.LoadLibrary)
- Host: GitHub
- URL: https://github.com/nh2/haskell-from-python
- Owner: nh2
- Created: 2013-01-08T19:11:17.000Z (over 12 years ago)
- Default Branch: master
- Last Pushed: 2013-01-08T20:35:23.000Z (over 12 years ago)
- Last Synced: 2025-04-09T04:12:56.518Z (about 2 months ago)
- Language: Haskell
- Size: 109 KB
- Stars: 58
- Watchers: 9
- Forks: 6
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
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README
haskell-from-python
===================
Example how to call Haskell from Python easily (using ctypes.cdll.LoadLibrary).
Originally from: https://bitbucket.org/darq/haskellfrompython
How to run the example
----------------------
Use `make` to compile the Haskell and C helper code.
Then run `python program.py` to run the example.
You might need to adjust some paths or versions in the `Makefile`.
Explanation
-----------
The Haskell function we want to call is `fibonacci :: Int -> Int` in `Example.hs`, and there is corresponding FFI function `fibonacci_hs`.
This Haskell code is compiled into a `libffi-example.so` object file loaded with `ctypes.cdll.LoadLibrary` in Python.
On the returned object, you can then call `fibonacci_hs(5)`.
Because the main entry point is now from Python instead from Haskell, we have to start the Haskell runtime system ourselves.
There is a small C wrapper `wrapper.c` to do that which is compiled into the object file together with the Haskell code.
### Removing the C wrapper
You can also entirely remove the C wrapper, if you like, and immediately call from Python:
```python
lib.hs_init(0, 0) # Instead of lib.example_init()
# ...
lib.hs_exit() # Instead of lib.example_exit()
```
It is your choice if you prefer this; the mediating C file type-checks it agains `HsFFI.h` so that you don't forget the `(0, 0)` arguments (this would result in a segfault) and that you get a compile-time error in case one of these functions changes in future.