Insurance

Migration from Haskell Monolith to .NET 8 Agility: Insurance System Transformation

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Emerline completely re-engineered a core insurance workflow system, migrating from niche Haskell to a modern, maintainable .NET 8 stack. The project unified the client's technology ecosystem and eliminated the dependency on rare developer skills.

Client and Challenge

The client, a large insurance company, depended on a core system for insurance workflows written in Haskell. This technology choice created several critical issues that constrained business growth. The original solution was a highly coupled monolith that was difficult to maintain and integrate into the primary .NET ecosystem. Key constraints included:

  • Niche skill dependency: Haskell requires rare developer skills, complicating recruitment, training, and retention.
  • Poor integration: The niche technology had limited compatibility with the client's predominantly .NET-based infrastructure.
  • High technical risk & debt: The complexity of the migration was exacerbated by undocumented legacy code and the deep tie between business logic and functional programming abstractions.
  • Scalability & maintenance limitations: The monolithic nature and outdated architecture limited the pace of innovation, new integrations, and UI improvements.
  • Migration complexity: Business logic was deeply tied to functional programming abstractions, requiring precise translation into an object-oriented .NET design.

Methodology and Approach

Emerline's approach focused on minimizing operational risk while ensuring the complete and accurate transfer of critical business logic, using an integrated Agile methodology (Scrum) tailored for complex enterprise platforms.

1:1 logic preservation

The core strategy was to execute a 1:1 logic migration by accurately translating complex functional programming rules from Haskell into an object-oriented .NET 8 design, ensuring critical business rules were preserved.

Modular architecture design

A new, modular, and service-oriented architecture was developed to enable scaling, parallel development work, and improved long-term maintainability.

Dependency validation

Interfaces and mocks were used extensively to simulate and validate complex legacy dependencies from the legacy system during the re-implementation process.

Quality assurance & CI/CD

A robust quality process was established, including the migration and expansion of unit tests, as well as the setup of Continuous Integration/Continuous Deployment (CI/CD) pipelines with static analysis tools such as SonarQube.

Phased rollout

The transition was performed gradually, starting with test and staging environments, followed by a careful production deployment.

Solution

The project resulted in a fully re-implemented platform on .NET 8, achieving a high-performance, modular, unified, and reusable solution. The transformation was executed by applying a meticulous methodology to future-proof the system while maintaining the integrity of the business logic.

Modular architecture

We approached the migration by first analyzing the Haskell modules to understand their dependencies, responsibilities, and how each part of the code supported the business logic and system workflows. Based on this mapping, we designed clear .NET interfaces that reflected the original functional boundaries, then migrated and adapted the existing tests to preserve behavior. Only after the contracts and tests were in place did we implement the .NET code, ensuring full functional parity with the original system.

1:1 logic preservation

The core business logic was migrated and precisely translated from complex functional programming abstractions in Haskell to an object-oriented .NET design, ensuring that all functional rules and existing JSON-based workflows were maintained.

Unified technology stack

By aligning the core system with the client's existing .NET infrastructure, the project eliminated the previous fragmented technology stack, simplifying maintenance and integration across the enterprise.

Technology Stack

The target solution is built around a modern and maintainable .NET stack, designed for scalability and high performance.

Target platform

.NET 8

Legacy system

Haskell

Architecture

Modular / Service-Oriented

Quality & analysis

Automated testing

SonarQube

Dependency management

Interfaces

Mocks

Results

The project successfully transitioned the client from technology constraints to business agility.

Key outcomes:

  • Accelerated development: By restructuring the system into independent modules, the development process became faster and more predictable, enabling more frequent releases and quicker adaptation to market needs.
  • Reduced technical debt: Comprehensive core refactoring and migration to modern .NET standards streamlined the maintenance process, improving code readability and minimizing risks during change implementation.
  • Improved user experience: Users have noted that the system has become considerably easier and more comfortable to work with; the platform now feels faster, more stable, and more reliable in daily use.
  • Foundation for future growth: The new architecture established a strong foundation for future expansion, allowing the company to securely and efficiently extend its product capabilities.