Types are used to both define how data is represented in memory and to restrict which values are allowed. For instance, an enum might be internally represented as a byte, but the compiler further restricts the permitted values to those the enum represents, and limits what operations are available (e.g. we can multiple a u8 by a u8, but not an enum by an enum).
In this sense, most statically-typed languages conflate how data is structured with how it is restricted. Some overlap is unavoidable, as anything represented by a single byte is always going to be restricted to at most 256 values, but Clojure tends to take the view that the more decoupling (or decomplecting) you can achieve the better.
This can be useful when dealing with data that is in some sense invalid. You might receive data that's outside expected bounds or even of a different type, and it might make sense to handle it in some fashion. This is a common necessity in pharmaceutical trials, for example.
In this sense, most statically-typed languages conflate how data is structured with how it is restricted. Some overlap is unavoidable, as anything represented by a single byte is always going to be restricted to at most 256 values, but Clojure tends to take the view that the more decoupling (or decomplecting) you can achieve the better.
This can be useful when dealing with data that is in some sense invalid. You might receive data that's outside expected bounds or even of a different type, and it might make sense to handle it in some fashion. This is a common necessity in pharmaceutical trials, for example.