Yesterday, I received a tweet announcing the release of a project called mathics that advertises itself as an open, lightweight alternative to mathematica. In fact, the documentation reads
"a tool for quick explorations and in educating people who might later switch to Mathematica".
I am in no way affiliated with the project but the little I played with it on the web interface I found that it did what it says on the package: I managed to define a function with upvalues, and all the (noncomplicated) rules and patterns I played with, worked out of the box as they would in Mathematica.
As it stands, based on the Mathematica.SE manifesto, a question of a user of mathics would be classified as "off-topic". This isn't much of a problem now that the user-base of that project is small but if it ever grows, I feel it would be a shame to ignore it.
On the other hand, having only played with mathics for a small amount of time I don't know what the differences are (first impression is that there is a major speed issue seeing as mathics is written in SymPy which is already slow) and how much incompatibility there is between the mathematica core language and that project.
So my question is: should we allow questions of mathics in the Mathematica.SE (we could add a relevant tag)?
If more experienced users would care to make a case for or against we could vote over it.
The open source variants just multiplied (although this time compatibility is guaranteed) :)
I was too quick to speak. Although this is out:
and it might also need its own tag, whatever kernel it's running isn't open-source :(