This module contains a compiler pass that adds all entries from imported modules to the environment.

Example

When a module A that exports a data type Foo

module A where

data Foo = Foo

is imported by a module B

module B where

import A

type Bar a = Foo -> a

then an entry for Foo is added to the environment under its original name A.Foo. The resolver pass will make sure that the reference to Foo in the declaration of Bar is resolved to A.Foo. Thus, the entry for Foo can be looked up in the translation of B.

When a module C imports B

module C where

import B

baz :: Bar ()
baz x = ()

both A.Foo and B.Bar are added to the environment of C since all entries imported by B are part of the B's module interface. In the example above this is needed among others during type inference. To infer the type of x the type synonym Bar needs to be expanded. The type of x is A.Foo. Thus, the corresponding entry must be visible. The resolver pass will make sure that C does not directly refer to the hidden entries of B's module interface.

Specification

Preconditions

Module interfaces for all imported modules must be available.

Translation

No modifications are made to the AST. All entries from module interfaces of imported modules are added to the environment. This includes entries that are not exported by the imported module.

Postconditions

All external entries that could be referenced (directly or indirectly) by the module are in the environment.

Error cases

• A fatal error is reported if there is an import for a module M but there is no such module interface available.