Surypus ERP/CRM
#

Система управления предприятием нового поколения на Haskell с формальной верификацией

License: MPL-2.0
Haskell
GHC
Stack
CI
codecov
Release
Issues
Pull Requests
Contributors
Stars
Wiki


Table of Contents
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Why Surypus?
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Traditional ERP systems are complex, error-prone, and expensive. Surypus offers a different approach:

  • Correctness by construction - Formal verification eliminates entire classes of bugs
  • Type safety - Haskell’s type system prevents runtime errors
  • Transparency - Open source means no vendor lock-in
  • Community-driven - Built by the community, for the community

Overview
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Surypus is a production-ready ERP/CRM system written in Haskell with emphasis on formal verification, type safety, and software correctness. It demonstrates the power of functional programming and formal methods in real-world business software.

Why Haskell?
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  • Type safety - Catch bugs at compile time
  • Purity - Predictable, testable code
  • Formal verification - Prove correctness with LiquidHaskell
  • Concurrency - Safe, composable parallelism
  • Performance - Compiled to native code

Why Surypus?
#

  • Formally verified - LiquidHaskell refinements prove invariants
  • Type-safe database - Persistent + Esqueleto prevent SQL injection at type level
  • Event sourcing - Complete audit trail
  • RBAC - 33 granular permissions
  • Production-ready - 61+ CI/CD workflows, comprehensive testing

Features
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Core ERP/CRM
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  • Accounting - General ledger, double-entry bookkeeping, trial balance
  • Inventory - Goods management, stock levels, warehouse operations
  • Tax - VAT calculations with formal verification
  • RBAC - 33 permissions, dynamic roles, audit logging
  • API - REST API with OpenAPI documentation
  • Event Sourcing - Complete audit trail, event replay
  • Reports - Balance sheet, income statement, inventory reports

Technical Features
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  • Formal Verification - LiquidHaskell refinement types
  • Type-Safe Database - Persistent + Esqueleto
  • REST API - Scotty web framework
  • JSON API - Aeson serialization
  • WebSocket - Real-time notifications
  • Authentication - JWT tokens, bcrypt password hashing
  • Docker - Multi-arch container builds
  • Nix - Reproducible builds

Quality Metrics
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MetricValue
Haskell modules486
Test suites69 files
Property-based tests3
Integration suites8
SQL test scripts116
RBAC permissions33
Code coverage80%+

Quick Start
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Prerequisites
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  • GHC 9.6.6 or later
  • Stack 2.13 or later
  • PostgreSQL 14 or later

Installation
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# Clone the repository
git clone https://github.com/surypus/surypus.git
cd Surypus

# Build the project
stack build

# Run tests
stack test

# Run the API server
stack run

Docker
#

# Build Docker image
docker build -t surypus .

# Run with Docker Compose
docker compose up

devcontainer
#

For a consistent development environment:

  1. Open in VS Code with Remote Containers extension
  2. Click “Reopen in Container”
  3. All tools and dependencies will be automatically installed

Documentation
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Getting Started
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Architecture
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Development
#

External Resources
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Contributing
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We welcome contributions! Please see our Contributing Guidelines for details.

Quick Start for Contributors
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  1. Fork the repository
  2. Create a feature branch: git checkout -b feature/your-feature
  3. Make your changes
  4. Run tests: stack test
  5. Format code: fourmolu -i src/ test/
  6. Commit and push
  7. Create a Pull Request

Code of Conduct
#

This project adheres to a Code of Conduct. By participating, you are expected to uphold this code.


Roadmap
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v2.0 Production Ready ✅
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  • Core infrastructure (Phases 160-171)
  • GUI & Features (Phases 13-21)
  • CI/CD pipeline with 61+ workflows
  • Docker support
  • Nix flake
  • devcontainer
  • Security hardening
  • Documentation

v2.1 Performance & Observability
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  • OpenTelemetry tracing
  • Prometheus metrics
  • Structured logging
  • Distributed tracing
  • Performance benchmarking

v3.0 Multi-Repo Architecture
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  • Extract surypus-core
  • Extract surypus-dal
  • Extract surypus-api
  • API gateway
  • Event bus

v4.0 Formal Verification
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  • LiquidHaskell coverage expansion
  • Property-based testing
  • Chaos engineering
  • GHC performance tracking

Community
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Surypus is more than just code - it’s a community of developers, users, and contributors who believe in the power of formal verification and type safety.

Getting Involved
#

Code of Conduct
#

This project adheres to a Code of Conduct. By participating, you are expected to uphold this code.


License
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Surypus is licensed under the Mozilla Public License 2.0.

Why MPL-2.0?
#

  • File-level copyleft - Changes to Surypus files must be shared
  • Compatible with proprietary code - Can be used in proprietary projects
  • Patent protection - Explicit patent grant from contributors
  • Simpler than GPL - Less restrictive for commercial use

Support
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Getting Help
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Reporting Security Issues
#

Please see our Security Policy for reporting vulnerabilities.

Commercial Support
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For commercial support, consulting, or custom development, please contact the maintainers.


Maintainer Resources
#

We’re committed to supporting the wellbeing of our maintainers. If you’re a maintainer or planning to become one, these resources are for you:

ResourceDescription
Maintainer Wellbeing & SustainabilityComplete guide to sustainable maintainership
Self Care GuideBurnout signs, motivation, energy management
Sustainability GuideTime/energy expectations, delegation, funding, automation
Rest PolicyPlanned and unplanned breaks, coverage plans
Boundaries GuideTime, scope, communication, emotional boundaries with templates
Blocking IssuesWhat to do when you’re stuck, escalation paths

Burnout Check
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Every Monday, a bot posts a weekly check-in issue to help maintainers reflect on their wellbeing. Feel free to respond or ignore as you prefer.

Your wellbeing comes first. Take breaks when you need them. Set boundaries without guilt.

Sponsors
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Surypus is supported by our amazing sponsors. Thank you! ❤️

Corporate Sponsors
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  • (No corporate sponsors yet - be the first!)

Individual Supporters
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  • (No individual supporters yet - be the first!)

Become a Sponsor
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If you find Surypus useful, please consider supporting us:

See FUNDING.md for all ways to support Surypus.


Acknowledgments
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Star us on GitHub if you find this project useful! ⭐

Made with ❤️ by the Surypus Team


Contributing
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Contributing to Surypus
#

Thank you for your interest in contributing to Surypus! This document provides guidelines and instructions for contributing to the project.

Table of Contents
#

Code of Conduct
#

This project and everyone participating in it is governed by our Code of Conduct. By participating, you are expected to uphold this code. Please report unacceptable behavior to the maintainers.

For details on how we enforce the Code of Conduct, see our Enforcement Guide.

Getting Started
#

Prerequisites
#

  • GHC 9.6.6 or later
  • Stack 2.13 or later
  • PostgreSQL 14 or later
  • Git 2.30 or later
  • Docker (optional, for containerized development)

Setting Up Development Environment
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  1. Fork the repository on GitHub
  2. Clone your fork locally:
    git clone https://github.com/YOUR_USERNAME/Surypus.git
    cd Surypus
  3. Add upstream remote:
    git remote add upstream https://github.com/surypus/surypus.git
  4. Install dependencies:
    stack build
  5. Run tests to verify setup:
    stack test

Using devcontainer (Recommended)#

For a consistent development environment, use the included devcontainer configuration:

  1. Open in VS Code with Remote Containers extension
  2. Click “Reopen in Container”
  3. All tools and dependencies will be automatically installed

How to Contribute
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Reporting Bugs
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Before creating a bug report, please check the existing issues to avoid duplicates.

When creating a bug report, include:

  • Clear title and description
  • Steps to reproduce the behavior
  • Expected behavior vs actual behavior
  • Environment details (OS, GHC version, Stack version)
  • Code samples or test cases if applicable
  • Screenshots if relevant

Use the Bug Report template for structured reports.

Suggesting Enhancements
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Enhancement suggestions are tracked as GitHub issues. When creating an enhancement suggestion:

  • Use a clear, descriptive title
  • Provide detailed description of the proposed feature
  • Explain why this enhancement would be useful
  • Include examples of how it would be used
  • Consider implementation details if possible

Use the Feature Request template for structured suggestions.

Development Workflow
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Branching Strategy
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We use a simplified Git Flow workflow:

  • main - stable production-ready code
  • feature/* - new features
  • bugfix/* - bug fixes
  • hotfix/* - urgent production fixes
  • release/* - release preparation

Workflow Steps
#

  1. Create a branch from main:

    git checkout main
    git pull upstream main
    git checkout -b feature/your-feature-name
  2. Make your changes following our code standards

  3. Write tests for new functionality

  4. Run tests locally:

    stack test
  5. Format code:

    fourmolu -i src/ test/
  6. Lint code:

    hlint src/ test/
  7. Commit changes following our commit message conventions

  8. Push to your fork:

    git push origin feature/your-feature-name
  9. Create a Pull Request against main

Code Standards
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Haskell Style
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  • Follow Haskell2010 standard
  • Use 2-space indentation (no tabs)
  • Maximum 100 characters per line
  • Use explicit imports (no wildcard imports)
  • Add Haddock comments to all public functions
  • Keep functions small and focused
  • Use meaningful names for types, functions, and variables

Module Organization
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-- Module header with description
-- | Brief description of the module purpose.
module Module.Name (exported, functions) where

-- Imports in order: external, qualified, local
import qualified Data.Text as T
import Data.Text (Text)

import Core.Tax
import DAL.Types

-- Type definitions
-- Function implementations
-- Property tests (if applicable)

Testing Standards
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  • Unit tests for all public functions
  • Property-based tests for invariants (QuickCheck)
  • Integration tests for database operations
  • Minimum 80% code coverage
  • Tests should be independent and deterministic

Documentation
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  • Haddock comments for all public APIs
  • README updates for new features
  • CHANGELOG entry for all changes
  • ADR (Architecture Decision Record) for significant decisions

Commit Messages
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We follow Conventional Commits specification:

<type>(<optional scope>): <description>

[optional body]

[optional footer(s)]

Types
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  • feat: New feature
  • fix: Bug fix
  • docs: Documentation changes
  • style: Code style changes (formatting, semicolons, etc.)
  • refactor: Code refactoring without behavior change
  • perf: Performance improvements
  • test: Adding or updating tests
  • build: Build system or dependency changes
  • ci: CI/CD configuration changes
  • chore: Other changes that don’t modify src or test
  • revert: Reverting previous changes

Examples
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feat(tax): add VAT calculation for reverse charge

Implement VAT calculation for reverse charge mechanism
used in B2B EU transactions.

Closes #123
fix(inventory): correct stock level calculation

Fixed off-by-one error in stock level calculation
when processing multiple concurrent transactions.

Fixes #456

Pull Request Process
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  1. Update documentation if your change affects public APIs
  2. Add tests for new functionality
  3. Ensure all tests pass locally
  4. Update CHANGELOG.md with your change
  5. Fill out the PR template completely
  6. Request review from at least one maintainer
  7. Address review feedback promptly and respectfully

PR Title Format
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Follow the same convention as commit messages:

feat(scope): description
fix(scope): description

PR Description
#

Your PR description should include:

  • What changes were made
  • Why the changes were necessary
  • How the changes were implemented
  • Testing that was performed
  • Screenshots if applicable
  • Related issues (use Closes #123 or Relates to #456)

Review Process
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For Contributors
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  • Respond to review comments within 7 days
  • Ask questions if feedback is unclear
  • Be open to suggestions and alternatives
  • Make requested changes in new commits (don’t force push)

For Reviewers
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  • Review PRs within 48 hours
  • Provide constructive, specific feedback
  • Approve with comments when minor changes are requested
  • Use conventional comments:
    • nit: Minor suggestion, not blocking
    • question: Needs clarification
    • issue: Must be addressed
    • praise: Highlight good practices

Community
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Communication Channels
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  • GitHub Issues: Bug reports and feature requests
  • GitHub Discussions: Questions and ideas
  • GitHub Wiki: Documentation and guides

Recognition
#

Contributors will be recognized in:

  • Release notes for significant contributions
  • CONTRIBUTORS.md file (coming soon)
  • GitHub contributors page

Maintainers
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Becoming a Maintainer
#

We welcome contributors who want to become maintainers. To be considered:

  1. Make consistent quality contributions for at least 3 months
  2. Demonstrate good communication and collaboration skills
  3. Show understanding of the project vision and goals
  4. Help review other contributors’ PRs
  5. Mentor new contributors

Responsibilities
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  • Review PRs within 48 hours
  • Triage issues within 48 hours
  • Maintain code quality and standards
  • Support the community
  • Make decisions in the best interest of the project

Time Commitment
#

We understand maintainers are volunteers. We ask for:

  • Minimum: 2-3 hours per week
  • Ideal: 5 hours per week
  • Flexibility: We accommodate different schedules and availability

Support
#

Maintainers have access to:

Questions?
#

If you have questions not covered here:

  1. Check the documentation
  2. Search existing issues
  3. Open a new discussion

Thank you for contributing to Surypus! 🚀

License
#

Mozilla Public License Version 2.0
==================================

1. Definitions
--------------

1.1. "Contributor"
    means each individual or legal entity that creates, contributes to
    the creation of, or owns Covered Software.

1.2. "Contributor Version"
    means the combination of the Contributions of others (if any) used
    by a Contributor and that particular Contributor's Contribution.

1.3. "Contribution"
    means Covered Software of a particular Contributor.

1.4. "Covered Software"
    means Source Code Form to which the initial Contributor has attached
    the notice in Exhibit A, the Executable Form of such Source Code
    Form, and Modifications of such Source Code Form, in each case
    including portions thereof.

1.5. "Incompatible With Secondary Licenses"
    means

    (a) that the initial Contributor has attached the notice described
        in Exhibit B to the Covered Software; or

    (b) that the Covered Software was made available under the terms of
        version 1.1 or earlier of the License, but not also under the
        terms of a Secondary License.

1.6. "Executable Form"
    means any form of the work other than Source Code Form.

1.7. "Larger Work"
    means a work that combines Covered Software with other material, in
    a separate file or files, that is not Covered Software.

1.8. "License"
    means this document.

1.9. "Licensable"
    means having the right to grant, to the maximum extent possible,
    whether at the time of the initial grant or subsequently, any and
    all of the rights conveyed by this License.

1.10. "Modifications"
    means any of the following:

    (a) any file in Source Code Form that results from an addition to,
        deletion from, or modification of the contents of Covered
        Software; or

    (b) any new file in Source Code Form that contains any Covered
        Software.

1.11. "Patent Claims" of a Contributor
    means any patent claim(s), including without limitation, method,
    process, and apparatus claims, in any patent Licensable by such
    Contributor that would be infringed, but for the grant of the
    License, by the making, using, selling, offering for sale, having
    made, import, or transfer of either its Contributions or its
    Contributor Version.

1.12. "Secondary License"
    means either the GNU General Public License, Version 2.0, the GNU
    Lesser General Public License, Version 2.1, the GNU Affero General
    Public License, Version 3.0, or any later versions of those
    licenses.

1.13. "Source Code Form"
    means the form of the work preferred for making modifications.

1.14. "You" (or "Your")
    means an individual or a legal entity exercising rights under this
    License. For legal entities, "You" includes any entity that
    controls, is controlled by, or is under common control with You. For
    purposes of this definition, "control" means (a) the power, direct
    or indirect, to cause the direction or management of such entity,
    whether by contract or otherwise, or (b) ownership of more than
    fifty percent (50%) of the outstanding shares or beneficial
    ownership of such entity.

2. License Grants and Conditions
--------------------------------

2.1. Grants

Each Contributor hereby grants You a world-wide, royalty-free,
non-exclusive license:

(a) under intellectual property rights (other than patent or trademark)
    Licensable by such Contributor to use, reproduce, make available,
    modify, display, perform, distribute, and otherwise exploit its
    Contributions, either on an unmodified basis, with Modifications, or
    as part of a Larger Work; and

(b) under Patent Claims of such Contributor to make, use, sell, offer
    for sale, have made, import, and otherwise transfer either its
    Contributions or its Contributor Version.

2.2. Effective Date

The licenses granted in Section 2.1 with respect to any Contribution
become effective for each Contribution on the date the Contributor first
distributes such Contribution.

2.3. Limitations on Grant Scope

The licenses granted in this Section 2 are the only rights granted under
this License. No additional rights or licenses will be implied from the
distribution or licensing of Covered Software under this License.
Notwithstanding Section 2.1(b) above, no patent license is granted by a
Contributor:

(a) for any code that a Contributor has removed from Covered Software;
    or

(b) for infringements caused by: (i) Your and any other third party's
    modifications of Covered Software, or (ii) the combination of its
    Contributions with other software (except as part of its Contributor
    Version); or

(c) under Patent Claims infringed by Covered Software in the absence of
    its Contributions.

This License does not grant any rights in the trademarks, service marks,
or logos of any Contributor (except as may be necessary to comply with
the notice requirements in Section 3.4).

2.4. Subsequent Licenses

No Contributor makes additional grants as a result of Your choice to
distribute the Covered Software under a subsequent version of this
License (see Section 10.2) or under the terms of a Secondary License (if
permitted under the terms of Section 3.3).

2.5. Representation

Each Contributor represents that the Contributor believes its
Contributions are its original creation(s) or it has sufficient rights
to grant the rights to its Contributions conveyed by this License.

2.6. Fair Use

This License is not intended to limit any rights You have under
applicable copyright doctrines of fair use, fair dealing, or other
equivalents.

2.7. Conditions

Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted
in Section 2.1.

3. Responsibilities
-------------------

3.1. Distribution of Source Form

All distribution of Covered Software in Source Code Form, including any
Modifications that You create or to which You contribute, must be under
the terms of this License. You must inform recipients that the Source
Code Form of the Covered Software is governed by the terms of this
License, and how they can obtain a copy of this License. You may not
attempt to alter or restrict the recipients' rights in the Source Code
Form.

3.2. Distribution of Executable Form

If You distribute Covered Software in Executable Form then:

(a) such Covered Software must also be made available in Source Code
    Form, as described in Section 3.1, and You must inform recipients of
    the Executable Form how they can obtain a copy of such Source Code
    Form by reasonable means in a timely manner, at a charge no more
    than the cost of distribution to the recipient; and

(b) You may distribute such Executable Form under the terms of this
    License, or sublicense it under different terms, provided that the
    license for the Executable Form does not attempt to limit or alter
    the recipients' rights in the Source Code Form under this License.

3.3. Distribution of a Larger Work

You may create and distribute a Larger Work under terms of Your choice,
provided that You also comply with the requirements of this License for
the Covered Software. If the Larger Work is a combination of Covered
Software with a work governed by one or more Secondary Licenses, and the
Covered Software is not Incompatible With Secondary Licenses, this
License permits You to additionally distribute such Covered Software
under the terms of such Secondary License(s), so that the recipient of
the Larger Work may, at their option, further distribute the Covered
Software under the terms of either this License or such Secondary
License(s).

3.4. Notices

You may not remove or alter the substance of any license notices
(including copyright notices, patent notices, disclaimers of warranty,
or limitations of liability) contained within the Source Code Form of
the Covered Software, except that You may alter any license notices to
the extent required to remedy known factual inaccuracies.

3.5. Application of Additional Terms

You may choose to offer, and to charge a fee for, warranty, support,
indemnity or liability obligations to one or more recipients of Covered
Software. However, You may do so only on Your own behalf, and not on
behalf of any Contributor. You must make it absolutely clear that any
such warranty, support, indemnity, or liability obligation is offered by
You alone, and You hereby agree to indemnify every Contributor for any
liability incurred by such Contributor as a result of warranty, support,
indemnity or liability terms You offer. You may include additional
disclaimers of warranty and limitations of liability specific to any
jurisdiction.

4. Inability to Comply Due to Statute or Regulation
---------------------------------------------------

If it is impossible for You to comply with any of the terms of this
License with respect to some or all of the Covered Software due to
statute, judicial order, or regulation then You must: (a) comply with
the terms of this License to the maximum extent possible; and (b)
describe the limitations and the code they affect. Such description must
be placed in a text file included with all distributions of the Covered
Software under this License. Except to the extent prohibited by statute
or regulation, such description must be sufficiently detailed for a
recipient of ordinary skill to be able to understand it.

5. Termination
--------------

5.1. The rights granted under this License will terminate automatically
if You fail to comply with any of its terms. However, if You become
compliant, then the rights granted under this License from a particular
Contributor are reinstated (a) provisionally, unless and until such
Contributor explicitly and finally terminates Your grants, and (b) on an
ongoing basis, if such Contributor fails to notify You of the
non-compliance by some reasonable means prior to 60 days after You have
come back into compliance. Moreover, Your grants from a particular
Contributor are reinstated on an ongoing basis if such Contributor
notifies You of the non-compliance by some reasonable means, this is the
first time You have received notice of non-compliance with this License
from such Contributor, and You become compliant prior to 30 days after
Your receipt of the notice.

5.2. If You initiate litigation against any entity by asserting a patent
infringement claim (excluding declaratory judgment actions,
counter-claims, and cross-claims) alleging that a Contributor Version
directly or indirectly infringes any patent, then the rights granted to
You by any and all Contributors for the Covered Software under Section
2.1 of this License shall terminate.

5.3. In the event of termination under Sections 5.1 or 5.2 above, all
end user license agreements (excluding distributors and resellers) which
have been validly granted by You or Your distributors under this License
prior to termination shall survive termination.

************************************************************************
*                                                                      *
*  6. Disclaimer of Warranty                                           *
*  -------------------------                                           *
*                                                                      *
*  Covered Software is provided under this License on an "as is"       *
*  basis, without warranty of any kind, either expressed, implied, or  *
*  statutory, including, without limitation, warranties that the       *
*  Covered Software is free of defects, merchantable, fit for a        *
*  particular purpose or non-infringing. The entire risk as to the     *
*  quality and performance of the Covered Software is with You.        *
*  Should any Covered Software prove defective in any respect, You     *
*  (not any Contributor) assume the cost of any necessary servicing,   *
*  repair, or correction. This disclaimer of warranty constitutes an   *
*  essential part of this License. No use of any Covered Software is   *
*  authorized under this License except under this disclaimer.         *
*                                                                      *
************************************************************************

************************************************************************
*                                                                      *
*  7. Limitation of Liability                                          *
*  --------------------------                                          *
*                                                                      *
*  Under no circumstances and under no legal theory, whether tort      *
*  (including negligence), contract, or otherwise, shall any           *
*  Contributor, or anyone who distributes Covered Software as          *
*  permitted above, be liable to You for any direct, indirect,         *
*  special, incidental, or consequential damages of any character      *
*  including, without limitation, damages for lost profits, loss of    *
*  goodwill, work stoppage, computer failure or malfunction, or any    *
*  and all other commercial damages or losses, even if such party      *
*  shall have been informed of the possibility of such damages. This   *
*  limitation of liability shall not apply to liability for death or   *
*  personal injury resulting from such party's negligence to the       *
*  extent applicable law prohibits such limitation. Some               *
*  jurisdictions do not allow the exclusion or limitation of           *
*  incidental or consequential damages, so this exclusion and          *
*  limitation may not apply to You.                                    *
*                                                                      *
************************************************************************

8. Litigation
-------------

Any litigation relating to this License may be brought only in the
courts of a jurisdiction where the defendant maintains its principal
place of business and such litigation shall be governed by laws of that
jurisdiction, without reference to its conflict-of-law provisions.
Nothing in this Section shall prevent a party's ability to bring
cross-claims or counter-claims.

9. Miscellaneous
----------------

This License represents the complete agreement concerning the subject
matter hereof. If any provision of this License is held to be
unenforceable, such provision shall be reformed only to the extent
necessary to make it enforceable. Any law or regulation which provides
that the language of a contract shall be construed against the drafter
shall not be used to construe this License against a Contributor.

10. Versions of the License
---------------------------

10.1. New Versions

Mozilla Foundation is the license steward. Except as provided in Section
10.3, no one other than the license steward has the right to modify or
publish new versions of this License. Each version will be given a
distinguishing version number.

10.2. Effect of New Versions

You may distribute the Covered Software under the terms of the version
of the License under which You originally received the Covered Software,
or under the terms of any subsequent version published by the license
steward.

10.3. Modified Versions

If you create software not governed by this License, and you want to
create a new license for such software, you may create and use a
modified version of this License if you rename the license and remove
any references to the name of the license steward (except to note that
such modified license differs from this License).

10.4. Distributing Source Code Form that is Incompatible With Secondary
Licenses

If You choose to distribute Source Code Form that is Incompatible With
Secondary Licenses under the terms of this version of the License, the
notice described in Exhibit B of this License must be attached.

Exhibit A - Source Code Form License Notice
-------------------------------------------

  This Source Code Form is subject to the terms of the Mozilla Public
  License, v. 2.0. If a copy of the MPL was not distributed with this
  file, You can obtain one at https://mozilla.org/MPL/2.0/.

If it is not possible or desirable to put the notice in a particular
file, then You may include the notice in a location (such as a LICENSE
file in a relevant directory) where a recipient would be likely to look
for such a notice.

You may add additional accurate notices of copyright ownership.

Exhibit B - "Incompatible With Secondary Licenses" Notice
---------------------------------------------------------

  This Source Code Form is "Incompatible With Secondary Licenses", as
  defined by the Mozilla Public License, v. 2.0.