Coalton infers and checks all types for pure Coalton code; there's no such thing as a dynamic or untyped expression.

Code that is untyped—Common Lisp code—is run in (lisp ...) forms [0] which requires the user to annotate the type and adds dynamic type checks to it to ensure it meets the contract the programmer specified.

[0] https://coalton-lang.github.io/manual/operators/lisp/