fix typo in type arguments

Author: bravit

README.md

@@ -140,7 +140,7 @@ Note similarly that you can write a certain kind of [take](http://hackage.haskel
 § 6. Didn't I hear that free monads are a dog from the point of view of efficiency?
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-We noted above that if we instantiate `Stream f m r` to `Stream ((,) a) m r` or the like, we get the standard idea of a producer or generator. If it is instantiated to `Stream f Identity m r` then we have the standard \_free monad construction/. This construction is subject to certain familiar objections from an efficiency perspective; efforts have been made to substitute exotic cps-ed implementations and so forth. It is an interesting topic.
+We noted above that if we instantiate `Stream f m r` to `Stream ((,) a) m r` or the like, we get the standard idea of a producer or generator. If it is instantiated to `Stream Identity m r` then we have the standard \_free monad construction/. This construction is subject to certain familiar objections from an efficiency perspective; efforts have been made to substitute exotic cps-ed implementations and so forth. It is an interesting topic.
 
 But in fact, the standard alarmist talk about *retraversing binds* and *quadratic explosions* and *costly appends*, and so on become transparent nonsense with `Stream f m r`\
 in its streaming use. The conceptual power needed to see this is basically nil: Where `m` is read as `IO`, or some transformed `IO`, then the dreaded *retraversing of the binds* in a stream expression would involve repeating all the past actions. Don't worry, to get e.g. the second chunk of bytes from a handle, you won't need to start over and get the first one again! The first chunk has vanished into an unrepeatable past.