This commit refactors the `Environment` struct to better manage the Rust
Runtime Library (RTL) bootstrap state.
A new `Rtl` struct is introduced to hold a frozen snapshot of the
initial RTL state, including scopes, types, purity, values, and
documentation. This snapshot is created once after `rtl::register()`
completes.
The `Environment::new()` constructor is updated to perform a two-phase
bootstrap: first, it registers RTL functions, and then it freezes the
scope 0 and captures the RTL state into the new `Rtl` struct.
A new constructor, `Environment::from_rtl()`, is added. This allows
creating independent execution environments that all share the same
underlying RTL state. This is crucial for isolation between different
execution contexts, as user definitions and loaded modules will not leak
between environments created from the same `Rtl` snapshot.
The `Environment::list_bindings` and `Environment::list_rtl_docs`
methods are updated to use the `rtl` field for accessing the RTL scope
and documentation, reinforcing the concept of a shared, immutable RTL
state.
A new test, `test_environments_from_shared_rtl_are_independent`, is
added to verify that environments created from the same `Rtl` snapshot
are indeed independent and do not leak user-defined bindings.
Brummel
893d9936ed