when is compilation necessary

suppose i have three modules:

module Foo(foo) where foo x = x + 1

module Bar(bar) where import Foo bar x = foo (x+1)

module Main(main) where import Bar main = print (foo 5)

Now, suppose I change Foo.hs so that "foo x = x + 2". If I ghc --make on Main, it will build Foo, then Bar, then Main, then link. Is all of this necessary or can I (manually) just rebuild Foo and then relink? -- Hal Daume III "Computer science is no more about computers | hdaume@isi.edu than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume