Stubbed Functions

AtomVM implements stub functions for certain BEAM operations that are either not applicable to embedded environments, not yet implemented, or intentionally left as no-ops for compatibility reasons. These functions allow BEAM code that references them to load and execute without errors, even though the actual functionality may not be present.

Purpose of Stubbed Functions

Stubbed functions serve several purposes in AtomVM:

Compatibility: Allow BEAM modules that use these functions to work anyway
Environment Differences: Functions that make no sense in embedded contexts (or in AtomVM) but are required for code compatibility
Performance: Operations that would be too expensive on microcontrollers and are safely ignored

List of Stubbed Functions

The following functions are currently stubbed in AtomVM and always return a fixed value:

I/O Functions

Module	Function	Return Value	Notes
`io`	`set_ops/1,2`	`ok`	Standard IO options are currently ignored

Other functions

Module	Function	Return Value	Notes
`string`	`jaro_similarity/2`	`0.0`

Important Considerations

When using AtomVM, be aware that stubbed functions will not provide the functionality you might expect from BEAM. Code that relies on these functions for critical behavior will need to be adapted for the AtomVM environment.

Detecting Stubbed Functions

To write portable code that works on both BEAM and AtomVM, you can detect the runtime environment:

case erlang:system_info(machine) of
    "BEAM" ->
        %% Use full functionality
        full_implementation();
    "ATOM" ->
        %% Use alternative approach or skip
        alternative_implementation()
end

Future Implementations

Some stubbed functions may be implemented in future versions of AtomVM. Use GitHub issues for providing any kind of feedback.