What is the relationship between unboxed types and strictness?

Question

Unboxed types, like Int#, and strict functions, like f (!x) = ..., are something different, but I see conceptual similarity - they disallow thunks/

Answer 1

Arguments of any types can be made "strict", but the only unboxed types that have corresponding boxed types are Char#, Int#, Word#, Double# and Float#.

If you know low-level languages like C, it's easier to explain. Unboxed types are like int, double, etc., and the boxed types are like int*, double*, etc. When you've got an int, you already know the whole value as it's represented in the bit pattern, therefore, it is not lazy. It must be strict too, as all values of int are valid and not ⊥.

However, given an int* you may choose to dereference the pointer later to get the actual value (thus lazy), and it is possible to have invalid pointers (it contains ⊥, i.e. non-strict).