store

The store module provides a lightweight, persistent key-value cache backed by the Erlang Process Dictionary.

In a standard file-backed REPL, every time the file is re-evaluated, all previous side-effects (like spawning processes or DB writes) would run again. GSH avoids this by wrapping every let binding in a cache check. This store ensures that variables are evaluated exactly once and kept alive in the VM’s memory across multiple REPL prompts.

Values

get

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pub fn get(key: String) -> a

Retrieves a value from the Process Dictionary by its key. Note: This is dynamically typed because the cache holds everything from basic integers to complex Erlang PIDs and custom types.

has

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pub fn has(key: String) -> Bool

Checks if a given key already exists in the Process Dictionary. The GSH evaluator uses this to determine if a binding’s side-effects need to be executed or if they can be skipped by fetching from the cache.

put

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pub fn put(key: String, value: a) -> a

Saves a value into the Process Dictionary under the given string key. Returns the saved value so it can be returned inline during evaluation.