3.1.4 The Current REPL Environment

Every REPL has a current environment, which is the place where expressions are evaluated and definitions are stored. When Scheme is started, this environment is the value of the variable user-initial-environment. There are a number of other environments in the system, for example system-global-environment, where the runtime system’s bindings are stored.

You can get the current REPL environment by evaluating

(nearest-repl/environment)

There are several other ways to obtain environments. For example, if you have a procedure object, you can get a pointer to the environment in which it was closed by evaluating

(procedure-environment procedure)

Here are some procedures that manage the REPL’s environment:

procedure: ge environment ¶

Changes the current REPL environment to be environment (ge stands for “Goto Environment”). Environment is allowed to be a procedure as well as an environment object. If it is a procedure, then the closing environment of that procedure is used in its place.

procedure: ve environment ¶

Starts a sub-REPL with it’s environment set to environment (ve stands for “Visit Environment”). Environment is allowed to be a procedure as well as an environment object. If it is a procedure, then the closing environment of that procedure is used in its place.

procedure: pe ¶

This procedure is useful for finding out which environment you are in (pe stands for “Print Environment”). If the current REPL environment belongs to a package, then pe returns the package name (a list of symbols). If the current REPL environment does not belong to a package then the environment is returned.