[Haskell-beginners] f . g or f g or f $ g?

[Martin Drautzburg]

Hello all

I frequently get confused over f . g vs f g. I do understand the following

With:

g :: a->b
f :: b ->c

f.g :: a->c

However 

f g 

is a type error, because then f would have to accept a function (a->b) as its 
first parameter, but it only accepts a b.

Is there a way to easily remember when to use f.g and when to use f g without 
having to do this type algebra.

-- 
Martin