Re: Re: OOP in Mathematica
- To: mathgroup at smc.vnet.net
- Subject: [mg29163] Re: [mg29151] Re: OOP in Mathematica
- From: Andrzej Kozlowski <andrzej at tuins.ac.jp>
- Date: Fri, 1 Jun 2001 04:15:26 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
This is true, but is not the whole truth. Mathematica has both genuine functions and symbols with re-write rules attached to them ( DownValues, UpValues and Subvalues) which can be said to mimic functions. The "genuine" functions are the built in functions, like Sin, and pure functions like #^2&. In the case of these functions it is indeed true that the "head is the function call", except that the function call may not take place if a re-write rule prevents it, e.g. In:= g_[x]^= 1; In:= #^2&[x] Out= 1 -- Andrzej Kozlowski Toyama International University JAPAN http://platon.c.u-tokyo.ac.jp/andrzej/ http://sigma.tuins.ac.jp/~andrzej/ on 01.5.31 0:28 PM, John Doty at jpd at w-d.org wrote: > In article <9f2g4c$878$1 at smc.vnet.net>, "Jens-Peer Kuska" > <kuska at informatik.uni-leipzig.de> wrote: > >> The head *is* the function call! > > No, the head is just the head. If a particular head is associated with > replacement rules that work like a function, you might want to call that > head a "function". On the other hand, you can invert function and argument > if you wish: > > In:= x_[sin]^:=Sin[x] > > In:= Pi[sin] > > Out= 0 > > To be sure, most rules mimic function evaluation and/or sequential flow of > control. This makes Mathematica look more like a "normal" programming > language than it really is. It's really just a convention: Mathematica can > also define bizarre rules like the ones above.