Proposal: modify `Read` instances for `Float` and `Double`

[Henning Thielemann]

On Tue, 28 Feb 2017, Iavor Diatchki wrote:

> This may affect existing programs---although it doesn't seem very likely.  Here is an example:
> 
> current behavior:
> 
> reads "0x10p10" = [(16.0,"p10")]
> 
> new behavior:
> 
> reads "0x10p10" = [(16384,"")]


"p" refers to a power of two and the exponent is written in decimal for a 
hexadecimal mantissa. Looks pretty confusing to me but it seems that the 
standard was made somewhen before this proposal.