Transducers are composable components for processing data independently of the context. So they can be used to process collections, streams, channels, etc. without knowledge of their input sources or output sinks.
The Clojure core library was extended in 1.7 so that the sequence functions like map, filter, take, etc. return a transducer when called without a sequence. Because transducers are functions with specific contracts, they can be composed using the normal
Performing Simple Mathematical Operations
This is how you would add some numbers in Clojure syntax. Since the method occurs as the first argument in the list, we are evaluating the + (or addition) method on the rest of the arguments in the list.