fid-listbuffer is a buffer implementation for the
Frigand Imperial Desktop. Fid buffers are
typically mutable monoids over particular unit
types; the exact unit type and the equations
satisfied by the monoid determine the particular
buffer type. This package defines a parametric
buffer type for the simple case of a free monoid
over a unit type that is to be exposed to the
programmer, where 'replaceableRegion' additionally
is equivalent to (\ r d -> return True).
