[astine]

If you don't know Clojure, you should know that Clojure has a sort of generic collection type called a 'sequence'. Arrays, Lists and Lazy Sequences are data structures that implement the sequence interface. There is a standard set of functions, 'map', 'reduce', 'filter' that operates on that sequence interface and provide a common set of functions for different kinds of datatypes. This lets the programmer reuse code and idioms and makes programs easier to understand overall.

The problem is that there are datatypes, such as streams and channels, which are fundamentally sequence abstractions but for one reason or other don't implement the 'sequence' interface. You could wrap them in a lazy sequence but that can be complex and will introduce a performance penalty. When they wrote core.async, they the authors found themselves reimplementing 'map', 'reduce' etc, for channels.

Transducers are a way to provide sequence operations to any kind of collection split the part that interfaces with the collection from the operation. This way we can dispense with the old 'map', 'filter', etc and just use transducers for everything. Because they're implemented with reducers, they're faster as well.

[susi22]

You're mixing up `seq` and `coll` here. Most of the stuff you said is not true.