[TxMt] Display pretty symbols in place of ASCII

Hi, I'm fairly new to TextMate but I've been through the mailing list archives and was unable to determine if the following is possible.

In general, I'd like TextMate to display a unicode character in place of a sequence of ASCII characters. For instance, I'd like to be able to type => but have the editor display ⇒ (U+21D2).

The saved file will need to be ASCII so I'm not looking for a way to replace characters, just a way to choose a different representation.

Is there a simple way to do this?

Thanks, Jonathan

-- ten ni hibari ningen umi ni asobu hi zo larks in the sky people in the sea a holiday