7.8 Static/Dynamic Typing Vis-à-Vis Explicit/Implicit Typing

The concepts of static/dynamic typing and explicit/implicit typing are sometimes confused and used interchangeably. The modifiers “static” or “dynamic” on “typing” (or “checking”) indicate the time at which types and type errors are checked. However, the types of those variables can be declared explicitly (e.g., int x = 1; in Java) or implicitly (e.g., x = 1 in Python). Languages that require the type of each variable to be explicitly declared use explicit typing; languages that do not require the type of each variable to be explicitly declared use implicit typing, which is also referred to as manifest typing (Table 7.1). Statically typed languages can use either explicit (e.g., Java) or implicit (e.g., ML and Haskell) typing. Dynamically typed languages typically use implicit typing (e.g., Python, JavaScript, Ruby). There are no advantages to using explicit typing in a dynamically typed language.