Typing Predef Module

The Typing/Predef Module handles the types for builtin types such as bools and ints.

build_initial_env

This function is called from the Compilation Driver via the route CompMisc.initial_env -> Env.initial_(un)safe_string. To prevent circular inclusion, the function takes add_type and add_exception parameters, which refer to the Env.add_type and add_extension functions, respectively.

• common_initial env is called, to create the main initial type environment.
• 2 exclusive variants of type environments are created, one with safe_string and one without. Both are returned as a pair, to be selected by the call from the Env Module.
• Within common_initial_env, basic types are created using the Types.type_declaration record. Every basic type is declared as an abstract type. A type like bool is a variant type with 2 identifiers, "true" and "false". Array and List are built-ins with generic type variables.
• Built-in exceptions are also created using the add_extension argument function.
• For each type, we call either Ident.create or Ident.create_predef_exn to store the identifiers.