@@ -191,6 +191,18 @@ the stages of a loop, it is often not useful to inline the whole loop
191191itself, in fact we may have to occasionally use a `NOINLINE` so that the
192192compiler does not inline it.
193193
194+We need to be careful about NOINLINE on polymorphic functions. When
195+NOINLINE is used, the function cannot be specialized causing huge
196+performance degradation. To avoid that we can either make the
197+function monomorphic or sometimes using `NOINLINE [0]` can do the
198+trick. `NOINLINE [0]` blocks inlining in earlier phases but lets it
199+specialize in the last phase, inlining in the last phase is left to
200+the compiler. `INLINE [0]` may sound the same as `NOINLINE [0]`,
201+however, it behaves differently because we ask the compiler to INLINE
202+it compulsorily and it may not give us the desired results. The
203+Data.Fold.writeLastN benchmark is one such case where `NOINLINE [0]`
204+provides much better performance than `INLINE [0]`.
205+
194206### NoSpecConstr
195207
196208It is not always useful to specialize function calls for all constructors, some