The 50g already does that as it has a built in CAS so symbolic is default. This are represented in their rational form or with respect to pi. 50g is basically

The 50g already does that as it has a built in CAS so symbolic is default. This are represented in their rational form or with respect to pi. 50g is basically a 48GX emulator with 400MHz ARM core that emulates Saturn, MetaKernel and a CAS. Goes like lightning. Oh and a bigger screen so you get 7-9 stack lines. Also you can use SD cards as ports. Mine has 256Mb of Flash. Eats a set of batteries once a month but it's worth it for the power. I can create a symbolic list with 50,000 entries in quite happily on the device then do all standard two-variable stats on it in 1-2 seconds.