merlin-mockup

A simplified mock-up of merlin-domains, used to experiment with multicore designs for Merlin.

Purpose

merlin-domains is an experimental branch of Merlin that uses two domains to improve performance. The mock-up reproduces the key concurrency patterns of merlin-domains in a smaller codebase, making it easier to prototype and evaluate design choices.

The three features explored are:

• Early type return: the typer domain shares a partial result with the main domain as soon as possible, so the main domain can start analysis without waiting for the full buffer to be typed.
• Parallelization: typing and analysis run concurrently on the partial result.
• Cancellation: if a new request arrives while the typer is still working, the main domain cancels the current work.

Architecture

The mock-up uses two domains:

• Main domain: listens for requests, dispatches work, runs analysis, and responds.
• Typer domain: receives configurations through a message-passing structure (Hermes), runs a simplified typer (Moparser), and shares results back.

Key modules:

Module	Role
merlin_mockup.ml	Entry point, spawns both domains
hermes.ml	Message-passing and synchronization between domains
mopipeline.ml	Orchestrates the typing pipeline
motyper.ml	Simplified typer with partial result support
moquery_commands.ml	Analysis on the (partial) typed result
server.ml	TCP server, parses requests

Build and run

To build the mock-up, run:

dune build

To run the tests, execute:

dune runtest ./tests/test.t

OxCaml portabilization

The oxcaml branch contains a portabilization of this mock-up to OxCaml, exploring how OxCaml's mode system can enforce data-race freedom at compile time. See the experience report for details.