Compatibility, but never at the expense of design.  Those

few places we thought we could make a clear improvement

we did so.  The reason there are so few of these is because

Scheme is already such a clean and simple language.

For new features we erred on the side of doing nothing

rather than adding a workaround or wart.  I think the large

language should be less conservative in new features

(how much so is debatable), but if you really want compatibility

regarding hash function APIs, just abandon salt/bounds rather

than adding ugly workarounds.

-- 

Alex