hello_nim.md

Testing

This gets compiled and run with:

./rusthon.py ./examples/hello_nim.md

Note you need to have Nim installed in your home directory so Rusthon can find it.

Nim

Below is a simple function in Nim. The Nim compiler is used to transform this to C.
The Nim runtime and generated code is then merged into a single C file and built as a static library by Rusthon.
This static library is then linked to the final C++ exe below.

The Nim program below is parsed by Rusthon, any functions that export to C using the pragma {.cdecl, exportc.} will have wrappers generated for them so they can be called when linked to the final C++ exe. The wrapper functions are declared as extern "C".

proc my_nim_function( a:cint, b:cint, s:cstring ): cint {.cdecl, exportc.} =
	echo("calling my_nim_function")
	echo(s)
	echo("a:", a)
	echo("b:", b)
	result = a+b

Rusthon

note: nim must be imported and nim.main must be called before calling any nim functions. note: below in the call to my_nim_function the string s is wrapped to cstr to convert it to a C string type const char*

#backend:c++
import nim

def main():
	nim.main()
	print 'calling nim function'
	s = 'mymessage to nim'
	msg = my_nim_function( 10, 20, cstr(s) )
	print msg
	print 'ok'

TODO

• return a cstring and convert it to a std::string
• fix return cstring when trying to call GC_ref(result) nim throws this error:

Error: type mismatch: got (cstring)
but expected one of: 
system.GC_ref(x: seq[T])
system.GC_ref(x: string)
system.GC_ref(x: ref T)