I want a function that takes expressions of the following form:
a$x and converts them to
In particular, consider the following test cases
exp = a$x + b$x$y + a$x[d] + a$x[d$y]
Should become, with some
ToFunctionNotation[exp] == a[x] + b[x][y] + a[x][d] + a[x][d[y]]
Note: I want to keep this as an expression for further processing. I tried using matches with
SymbolName and string patterns, but couldn't figure it out.