[9] Clean shares many properties and syntax with a younger sibling language, Haskell: referential transparency, list comprehension, guards, garbage collection, higher order functions, currying, and lazy evaluation.

However, Clean deals with mutable state and input/output (I/O) through a uniqueness type system, in contrast to Haskell's use of monads.

[10] An integrated development environment (IDE) for Microsoft Windows is included in the Clean distribution.

This, combined with compiling to native code, makes Clean programs which use high abstraction run relatively fast according to The Computer Language Benchmarks Game.

Although Clean is typically used to generate native executables, several projects have enabled applications in web browsers.