MessageFormat is pretty handy when dealing with complex messages with date, number, percent, plural, etc.
When formatting percentage, it'd be great if I could control the number of digits (integer portion and fraction portion) as I can do with just 'number formatter'.
does not work because '%' is literally interpreted. In some locales, there should be a space before '%' sign, but with the above, I don't get that right.
Obviously, the percentage portion can be formatted separately and inserted into a string.
However, it'd be handy if a message format can be extended to allow the control of # of digits. Below are two possible ways to extend message format.
A similar approach may be taken for the currency.