I am working on a small GHC extension to support floating point literals in hexadecimal notation (https://github.com/ghc-proposals/ghc-proposals/pull/37), which is similar to what's available in other languages.

To support this change, I would like to propose that we modify the `Read` instances for `Float` and `Double` to parse literals in the new notation.

This may affect existing programs---although it doesn't seem very likely.  Here is an example:

current behavior:

new behavior:

What do people think?

-Iavor