Express polynomials evaluation using foldr1

Old version had gratious multiplication. For example following
would be genrated for ax^3 + bx^62 +  cx + d assuming that everything
is inlined:

d + (c + (b + (a + 0*x)*x))*x

New version avoid multiplication by 0. Check for null vector
does not brack fusion.

For some reason performance is improved all cases. Even if vector is
large and not inlined.

Numeric/Polynomial.hs

@@ -34,8 +34,9 @@ evaluatePolynomial :: (Vector v a, Num a)
                    -> v a  -- ^ Coefficients
                    -> a
 {-# INLINE evaluatePolynomial #-}
-evaluatePolynomial x
-  = G.foldr (\a r -> a + r*x) 0
+evaluatePolynomial x v
+  | G.null v  = 0
+  | otherwise = G.foldr1 (\a r -> a + r*x) v
 
 -- | Evaluate polynomial with only even powers using Horner's method.
 -- Coefficients starts from lowest. In pseudocode: