How to read scalar, vector and matrix information in string format resembling Python syntax in R?

I have strings that contain scalars, vectors, and matrices, e.g.

"[0,1],[[1,2],[3,4]],42"

And following the same example, that input in R should give me this:

[[1]][1] 0 1[[2]]     [,1] [,2][1,]    1    3[2,]    2    4[[3]][1] 42

So the notation is similar to that of Python where matrices are actually lists of lists.

Should I just write a parser for this, or has somebody already done that or is there a simple and neat trick to achieve this with no or only a little effort?