Rumoca

Try Rumoca in your browser! - No installation required.

A Modelica compiler written in Rust. Rumoca parses Modelica source files and exports to the DAE IR Format (supporting both implicit and explicit model serialization), or via user-customizable templates using MiniJinja. The DAE IR format is consumed by Cyecca for model simulation, analysis, and Python library integration with CasADi, SymPy, and other backends.

Note: Rumoca is in early development. While already usable for many practical tasks, you may encounter issues. Please file bug reports to help improve the compiler.

Quick Start

# Install
cargo install rumoca

# Compile to DAE IR (JSON)
rumoca model.mo -m MyModel --json > model.json

# Format Modelica files
rumoca-fmt

# Lint Modelica files
rumoca-lint

Installation

Rust (Compiler, Formatter, Linter)

cargo install rumoca

Python

The Python package bundles the Rust compiler, so no separate Rust installation is needed:

pip install rumoca

import rumoca

# Compile a Modelica file
result = rumoca.compile("model.mo")

# Get as JSON string or Python dict
json_str = result.to_base_modelica_json()
model_dict = result.to_base_modelica_dict()

# Compile from string
result = rumoca.compile_source("""
    model Test
        Real x(start=0);
    equation
        der(x) = 1;
    end Test;
""", "Test")

Rust Library

[dependencies]
rumoca = "0.7"

use rumoca::Compiler;

fn main() -> anyhow::Result<()> {
    let result = Compiler::new()
        .model("MyModel")
        .compile_file("model.mo")?;

    let json = result.to_dae_ir_json()?;
    println!("{}", json);
    Ok(())
}

Tools

MSL Compatibility

Rumoca is tested against the Modelica Standard Library 4.1.0.

Partial models have external connector flow variables that receive equations when connected in a larger system.

Benchmark (AMD Ryzen 9 7950X, 16 cores):

Caching:

• In-memory caches (extends chain, resolved classes): Built during flatten phase (~1.5s), reset between runs
• DAE disk cache (~/.cache/rumoca/dae/): Stores compiled model results, provides 6x speedup on balance phase

# Run the MSL balance test
cargo test --release test_msl_balance_all -- --ignored --nocapture

# Clear disk caches for cold-start benchmark
rm -rf ~/.cache/rumoca/ast ~/.cache/rumoca/dae

Custom Code Generation

Rumoca supports MiniJinja templates for custom code generation:

rumoca model.mo -m MyModel --template-file examples/templates/casadi.jinja > model.py
rumoca model.mo -m MyModel --template-file examples/templates/sympy.jinja > model.py

Example template:

# Generated from {{ dae.model_name }}
{% for name, comp in dae.x | items %}
{{ name }}: {{ comp.type_name }} (start={{ comp.start }})
{% endfor %}

See examples/templates/ for complete examples (CasADi, SymPy, Base Modelica).

VSCode Extension

Search for "Rumoca Modelica" in the VSCode Extensions marketplace, or install from the marketplace page.

The extension includes a bundled rumoca-lsp language server - no additional installation required.

Features:

• Syntax highlighting (semantic tokens)
• Real-time diagnostics with type checking
• Autocomplete for keywords, built-in functions, and class members
• Go to definition / Find references
• Document symbols and outline
• Code formatting
• Hover information
• Signature help
• Code folding
• Inlay hints
• Code lens with reference counts
• Rename symbol
• Call hierarchy
• Document links

Configuring Library Paths:

{
  "rumoca.modelicaPath": [
    "/path/to/ModelicaStandardLibrary",
    "/path/to/other/library"
  ]
}

Alternatively, set the MODELICAPATH environment variable. See the extension documentation for details.

WebAssembly (Browser)

Rumoca compiles to WebAssembly, enabling browser-based Modelica compilation without a backend server.

Features:

• Parse and compile Modelica models in the browser
• DAE IR (JSON) generation
• Template rendering with MiniJinja
• Multi-threaded compilation using Web Workers

Try the Demo:

./tools/wasm-test.sh
# Open http://localhost:8080/examples/wasm_editor/index.html

The demo provides a Monaco-based editor with:

• Split-pane Modelica and Jinja2 template editing
• Real-time template preview
• DAE IR JSON export
• Autocomplete for template variables (dae.x, dae.u, etc.)

Building WASM:

Integration with Cyecca

rumoca model.mo -m MyModel --json > model.json

from cyecca.io.rumoca import import_rumoca

model = import_rumoca('model.json')
# Use model for simulation, analysis, code generation, etc.

Architecture

Modelica Source -> Parse -> Flatten -> BLT -> DAE -> DAE IR (JSON)
                   (AST)   (Flat)    (Match)  (DAE)
                                                          |
                                                       Cyecca
                                                          |
                                               CasADi/SymPy/JAX/etc.

Structural Analysis:

• Hopcroft-Karp matching (O(E√V)) for equation-variable assignment
• Tarjan's SCC algorithm for topological ordering and algebraic loop detection
• Pantelides algorithm for DAE index reduction (detects high-index systems)
• Tearing for algebraic loops (reduces nonlinear system size)

Development

cargo build --release   # Build
cargo test              # Run tests
cargo fmt --check       # Check Rust formatting
cargo clippy            # Lint Rust code
rumoca-fmt --check      # Check Modelica formatting
rumoca-lint             # Lint Modelica files

rumoca-fmt                              # Format all .mo files
rumoca-fmt --check                      # Check formatting (CI mode)
rumoca-fmt model.mo                     # Format specific files
rumoca-fmt --config indent_size=4       # Custom indentation

indent_size = 2
use_tabs = false
max_line_length = 100
blank_lines_between_classes = 1

rumoca-lint                     # Lint all .mo files
rumoca-lint --level warning     # Show only warnings and errors
rumoca-lint --format json       # JSON output for CI
rumoca-lint --list-rules        # List available rules
rumoca-lint --deny-warnings     # Exit with error on warnings

min_level = "warning"
disabled_rules = ["magic-number", "missing-documentation"]
deny_warnings = false

Caching

Rumoca uses multi-level caching: in-memory caches for session-level performance (parsed classes, resolved definitions), and a persistent disk cache (~/.cache/rumoca/dae/) that works like ccache for CI pipelines. The disk cache is invalidated when source files or the compiler version change.

Roadmap

Export Targets:

• eFMI/GALEC

Import Targets:

• Base Modelica (MCP-0031) - interface with OpenModelica, Dymola, etc.

Contributing

Contributions welcome! All contributions must be made under the Apache-2.0 license.

License

Apache-2.0 (LICENSE)

Citation

@inproceedings{condie2025rumoca,
  title={Rumoca: Towards a Translator from Modelica to Algebraic Modeling Languages},
  author={Condie, Micah and Woodbury, Abigaile and Goppert, James and Andersson, Joel},
  booktitle={Modelica Conferences},
  pages={1009--1016},
  year={2025}
}

See Also

• Modelica IR - DAE IR specification
• Cyecca - Model simulation, analysis, and code generation
• Modelica Language