u/gallaisin r/haskell • Recommends
On “Fast Haskell: Competing with C at parsing XML”
If you look at the code, you'll see that calls to `elemIndexFrom` are immediately cased on to dispatch between `Just` and `Nothing`. My intuition is that adding the `INLINE` pragma to `elemIndexFrom` gives Haskell the opportunity to fire some optimizations. This HIW talk goes into more details on related matters.