H-E-B Successfully Migrates Mainframe to Haskell
Texas-based retail giant H-E-B has transitioned from COBOL mainframes to Haskell, now running approximately one million lines of production Haskell code. Engineers share insights on the project’s journey and challenges.
Texas-based retail giant H-E-B has successfully transitioned its core systems from COBOL-based mainframes to Haskell, with roughly one million lines of Haskell code now running in production. This initiative was not merely a language migration but a large-scale project to transfer decades of business logic into a modern architecture. Joshua Miller, an engineer at H-E-B, shared detailed insights into the project in an article published on Haskell’s official blog.
Mainframe Limitations
When Miller joined H-E-B in 2018, the company’s core systems were still supported by COBOL-based mainframes. As Texas’s largest private company in the retail sector, H-E-B’s primary focus has always been ensuring shelves are stocked for its customers, regardless of the systems working behind the scenes. The mainframe had served this purpose reliably for decades.
However, customer expectations have evolved. Digital features like curbside pickup, home delivery, real-time inventory tracking, and in-store searches have emerged only in the past decade. Meeting these demands required expanding the supply chain infrastructure connecting over 435 stores and distribution centers. The existing mainframe, however, was not designed to scale in this way.
Like many other companies, H-E-B considered moving its mainframe systems to the cloud. However, a simple “lift and shift” strategy risked losing the institutional knowledge embedded in the decades-old business logic. Breaking down the monolithic application, which managed hundreds of database tables, into microservices that autonomous teams could handle posed significant technical and organizational challenges.
A Leap to Lambda
In this context, consultants proposed Haskell as a solution. Using Haskell as a common language, the company launched a new project to replace its largest mainframe application. Miller, who joined the project early on, expressed his excitement about using Haskell for a real-world, impactful initiative.
What began as an experimental effort has now evolved into multiple production systems powering critical supply chain applications. Eight years later, H-E-B maintains roughly one million lines of Haskell code, managed by several teams across various domains. Although the project has achieved notable success, it has not been without challenges.
Barriers to Adopting Haskell
Proposing a programming language as a business solution is no small feat, Miller noted. Haskell, in particular, faces hurdles due to its low recognition and widespread resistance to functional programming languages. The project’s success can be attributed to Haskell’s type safety and expressiveness, which allowed the team to accurately model the complex business logic in the legacy systems. Another key factor was the team’s significant investment of time in learning the language.
Editorial Opinion
In the short term, H-E-B’s case could reignite interest in enterprise Haskell. The transition from mainframes to modern languages is a challenge faced by many companies, and Haskell’s demonstrable results in this context serve as a boost for the functional programming community. In particular, migrating from legacy languages like COBOL to Haskell is compelling, as the language’s robust type system aids in preserving business logic.
In the long term, Haskell may carve out a niche in the enterprise domain. However, its steep adoption barriers—including a challenging learning curve, library maturity, and talent acquisition—remain significant obstacles. Only organizations capable of committing to large-scale, long-term projects, like H-E-B, are likely to succeed with Haskell.
That said, as languages like Rust and Elixir gain traction with their functional programming features, the value of purely functional languages like Haskell may see renewed appreciation. From the editorial perspective, H-E-B’s achievement of running one million lines of Haskell in production underscores that this decision was not driven by language advocacy but by a clear alignment with business needs.
References
- “Enterprise Haskell at H-E-B”, by blog.haskell.org via Hecate — Lobsters, 2026-07-17T21:51:07.000Z (ARR)
- Source URL: https://blog.haskell.org/enterprise-haskell-at-h-e-b/
Frequently Asked Questions
- What specific applications at H-E-B are written in Haskell?
- The article describes them as "critical supply chain applications," but specific functions, such as inventory management or delivery optimization, are not disclosed. Further updates are awaited.
- Why did H-E-B choose Haskell over a simple cloud migration?
- A straightforward lift-and-shift to the cloud could not adequately modernize the organizational knowledge embedded in decades of business logic. Haskell’s type safety and expressiveness were deemed effective for accurately modeling this complex logic.
- Can other companies undertake a similar migration to Haskell?
- It is possible, but it requires significant investment in learning the language and a long-term commitment. Organizations must have the resources to sustain an eight-year project like H-E-B’s, and talent acquisition for Haskell, similar to COBOL, remains a challenge.
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