Re: MLPutFunction : how to put a pure function

*To*: mathgroup at smc.vnet.net*Subject*: [mg50050] Re: [mg49860] MLPutFunction : how to put a pure function*From*: Omega Consulting <info at omegaconsultinggroup.com>*Date*: Fri, 13 Aug 2004 05:55:45 -0400 (EDT)*References*: <200408041446.KAA20186@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

On Aug 4, 2004, at 9:46 AM, Zhu Chongkai wrote: > I am writing a Mathematica FrontEnd in C using Mathlink. > > How to put a expression such as "Function[z,z+1][5]" (from C to > Mathematica)? > The standard C function 'MLPutFunction' can't do that, because the > head of > the > expression is still a compound expression but not a symbol. > > The same situation happens when such a expression was returned from > Mathematica. > Obviously, 'MLGetFunction' can't do the job. I see 2 ways to do this: 1) Use the "text interface" of MathLink. This is where you send the entire expression as a sting. And Mathematica parses it, just like it were an In[]:=. char buf[50]="Function[z,z+1][5]"; long numchars = strlen(buf); MLPutNext(stdlink, MLTKFUNC); MLPutSize(stdlink, numchars); MLPutData(stdlink, buf, numchars); The reverse would be int type, num_bytes; char* buf; type = MLGetNext(stdlink); MLBytesToGet(stdlink, &num_bytes); buf = (char *)malloc(num_bytes+1); MLGetData(stdlink, buf, num_bytes, &num_bytes); buf[num_bytes] = '\0'; Note, all of this is boiled down code from FastBinaryFiles: http://library.wolfram.com/infocenter/MathSource/354/ 2) The second is to pull the head off and send as a separate expression. On the kernel side you recombine. This is equivalent to the kernel command: (f = Function[z, z+1]; f[5]) MLPutFunction(stdlink, "CompoundExpression", 2); MLPutFunction(stdlink, "Set", 2); MLPutSymbol(stdlink, "f"); MLPutFunction(stdlink, "Function", 2); MLPutSymbol(stdlink, "z"); MLPutFunction(stdlink, "Plus", 2); MLPutSymbol(stdlink, "z"); MLPutInteger(stdlink, 1); MLPutFunction(stdlink, "f", 1); MLPutInteger(stdlink, 5); Getting is a bit trickier. Instead of returning the compound expression (call it x), I'd return the head and arguments separately. That is {Head[x], Apply[List, x]}. That's something that can be parsed by the standard functions. ---------------------------------------------- Omega Consulting The final answer to your Mathematica needs. http://omegaconsultinggroup.com

**References**:**MLPutFunction : how to put a pure function***From:*"Zhu Chongkai" <zhuchongkai@online.sh.cn>