Lazaryev Yuriy

Senior Software Engineer

Software engineer with 25+ years of experience. Started in web development, went deep into backend and distributed systems. My interest in DSLs led me to compilers — I tried writing my own backend for a PureScript-to-Lua compiler, enjoyed it, and decided to do it full-time. That is how I ended up working on the smart-contract language compiler for Cardano.

I bring a design-before-build discipline that produces software correct and secure before it is fast — useful in domains where bugs have financial or safety consequences.

Experience

Jan 2024 - Present

Intersect MBO

Senior Software Engineer — Plutus Core Team

Intersect is the member-based organization stewarding the Cardano open-source ecosystem. As a compiler engineer on the Plutus Core team I work on the Plutus and Plinth compilers — the foundation of Cardano's smart contract platform.

  • Designed and built the UPLC-CAPE benchmarking framework: a structured harness for measuring Untyped Plutus Language Core (UPLC) program performance across compiler versions. Presented at the UPLC 2025 workshop.
  • Security review work on high-stakes blockchain code: auditing and hardening smart contract compiler output where on-chain bugs have real financial consequences.
  • Authored the concept and co-built an AI-assisted bug-discovery pipeline: I led a team of AI specialists, contributed a custom pipeline component (evaluation engine), and integrated the result into the compiler's existing tooling.
  • Cardano Node release manager: coordinated multi-team release process for cardano-node, including integration testing, changelog curation, and stakeholder sign-off.
  • Implemented CIP-57: a machine-readable format for documenting Plutus smart contract blueprints, enabling tooling to generate type-safe client code.
  • Authored and implemented CIP-0156 (multiIndexArray builtin): took the proposal from initial draft through community ratification to full compiler implementation. This is the standard path for extending the Cardano scripting language.
  • Implemented a Cardano blockchain indexer that continuously collects execution statistics on all Plutus scripts running on mainnet, feeding a Grafana dashboard used by the compiler team to make data-informed optimization decisions.
Feb 2022 - Dec 2023

Input-Output Global → Cardano Foundation

Senior Software Engineer — Cardano Wallet team

Full-time contributor to cardano-wallet, the production Haskell full-node wallet used by most exchanges integrating with Cardano. The team transitioned from IOG to the Cardano Foundation mid-2023 as part of a stewardship handover; codebase, team, and scope of work stayed the same — only the contracting entity changed.

  • Designed and shipped Light Backend Mode for the full-node wallet, letting users transact without waiting for a full chain sync by routing chain queries through an external indexing API. Owned the feature end-to-end — architecture, network layer, sync semantics, error handling, rate limiting — from initial design to production. Later retired when the team decided to drop the external-API dependency.
  • Rewrote the wallet's transaction-construction pipeline around a unified balancing primitive, replacing a legacy build-and-sign path that had diverged across endpoints. Migrated every transaction-producing API onto the new pipeline — core logic exercised by every transaction the wallet emits.
  • Remastered the end-to-end test infrastructure: turned a flaky shared suite into a reliable per-PR check, with the suite owning its own preprod node and wallet lifecycle and the local test cluster decoupled from the wallet codebase.
Aug 2019 - Jan 2022

Bellroy

Lead Software Engineer

Bellroy is an Australian e-commerce company that decided to pivot its backend from Ruby on Rails to Haskell after early success with Elm on the frontend. I joined as the founding Haskell engineer to establish the stack, practices, and team.

  • Designed and built a Haskell customer-behaviour simulation that modelled Bellroy's full purchase funnel. After a month of collaborative iteration the model was handed to the data science team, who used it as the foundation for their own analytical work — one of the cleaner examples of FP as a tool for exploratory research, not just production services.
  • Bet early on serverless: the first service I shipped used AWS Lambda and DynamoDB; it is still running in production with no major incidents. That durability signal convinced the team to make serverless the default deployment pattern. By the time I left, the estate had grown from 0 to 6 serverless services, each comprising multiple Lambda functions.
  • Led a 5-day on-site functional programming course for colleagues, then provided ongoing mentorship. Three colleagues transitioned to full-time Haskell development as a result.
  • Built a compiler framework for strongly-typed, composable e-commerce DSL compilers. Four DSLs emerged from this framework — covering shipping logistics and product promotion rules — and are in active production use.
  • Advised on the gradual monolith-to-distributed transition as the platform scaled horizontally, ensuring the new Haskell services could integrate cleanly with the existing Rails systems during the migration period.
Nov 2018 - Jul 2019

CollegeVine

Senior Software Engineer, Team Lead

CollegeVine is an edu-tech platform helping students navigate college admissions. Developed backend and frontend software, led a small team, and collaborated with product and UX. Key achievement: a UI test automation framework that significantly cut manual QA time.

Apr - Nov 2018

DSTOQ

Lead Software Engineer

DSTOQ was a fintech startup bringing fractional stock ownership to emerging markets, built on the Stellar blockchain. One of the first engineers hired; shaped the initial tech vision, architecture, and security foundation.

  • Designed the core architecture and security model for a system where financial correctness is a hard requirement, not a quality goal. Developed mission-critical components in Haskell with extensive property-based tests (QuickCheck, Hedgehog).
  • Wrote and open-sourced the Haskell Stellar SDK (https://github.com/Unisay/stellar-haskell-sdk) — the first community SDK for Stellar in Haskell, enabling integration with the XLM payment network.
  • Conducted technical interviews and coordinated external contractors.
Jun 2015 - Mar 2018

Zalando

Senior Software Engineer

Zalando is Europe's largest online fashion retailer. Worked on the merchant and partner platform, participated in architecture decisions, and helped hire new engineers.

  • Single-handedly developed both the frontend and backend for the integration of miadidas.com into the Zalando shop, working directly with Adidas colleagues across two codebases simultaneously.
  • Actively involved in technical architecture decisions and interviewing as the team grew from a small FP pilot to a larger Haskell/Scala group.
Feb 2013 - Jun 2015

Groupon

Senior Software Engineer

Groupon was the world's largest local-deal aggregator. Developed software applying machine learning to big data — both batch processing (Hadoop) and real-time search relevance. Implemented a lambda architecture for big data. Key achievement: a reactive distributed data indexer for real-time search.

Mar - Aug 2012

Rule Financial

Lead Software Engineer

Rule Financial is a fintech consultancy. Led a team building the Prime Transaction Manager product for Barclays Capital. Primary achievement: refactoring a 10+ year legacy codebase and modernising the deployment pipeline.

Jun 2007 - Mar 2012

Zoral Labs

Senior Java Developer

Consulting shop with clients across the US and Europe. Worked on projects for Numara Software (ITIL workflow platform, acquired by BMC), GreenLink Networks (loyalty programme platform on JBoss/EJB), Returnil (antivirus + virtualisation product serving 1M clients), and Fizzback (real-time customer feedback via JBPM). Also contributed a semantic similarity NLP research component in collaboration with a Ukrainian university linguist.

Aug 2005 - Jun 2007

Inform-mobil

Senior Software Developer

Mobile services company working with Ukrainian operators (MTS, KyivStar, Beeline). Developed and managed Internet, WAP, SMS, STK, and IVR services under high load. Built a WAP search engine with morphology support and a crawler. Integrated the Ukrainian national lottery with a mobile operator portal.

Dec 2003 - Aug 2005

IT Agency "Green Island"

Web Developer

Built a CMS used to deliver ~50 customer websites including clients in banking, insurance, and government (Hydrometeorological Centre, Federal Educational Oversight Service).

Oct - Nov 2003

Moscow Local Internet Provider "Lianet"

Software Developer

In two months, independently developed a customer support and order processing system in Perl on FreeBSD.

Dec 2002 - Oct 2003

Company "Association Ltd."

Web Developer

Developed and maintained intranet portal and public-facing e-shop. Integrated the web shop with the company's proprietary ERP system.

Jul 2001 - Jan 2003

University "Ukraine"

System Administrator

Ran computer labs during my studies. Installed campus LAN with NAT and firewall. Developed a remote workstation management tool in Delphi/Object Pascal. Maintained the electronic testing system used for exam data collection.

Jun 1999 - Oct 2003

Regional ISP "ReIS"

System Administrator

Server and dial-up modem pool support. Domain registration for clients. Gained foundational experience with FreeBSD, routing, Sendmail, Apache, Squid, BIND, IPFW.

Skills

Functional Programming & Formal Methods

HaskellPureScriptElmModel Checking (Quint, TLA+, Agda)

Compiler & PL Engineering

Plutus CorePlinthUntyped Plutus Core (UPLC)DSL designBenchmarkingGHC CoreGHC Plugins

Blockchain & Smart Contracts

CardanoPlutusPlinthStellarCIP authorshipSecurity

Cloud & Infrastructure

AWS LambdaEC2 / S3 / RDSDynamoDBEKSServerlessDockerNixNixOSTerraformCI/CD (GitHub Actions)

Data & Search

PostgreSQLElasticsearchKafkaRedisRabbitMQHadoopGraphQL

JVM Ecosystem

J2EESpringDropwizardAkkaScalaClojureGroovyScalazTypelevel Cats

Projects

PureScript to Lua: compiler backend

A custom backend for the PureScript compiler targeting Lua. Written as a hobby project to explore DSL design and compiler construction; this experience led directly to my move into professional compiler engineering.

UPLC-CAPE Benchmarking Framework

A structured benchmarking harness for Untyped Plutus Language Core (UPLC) programs. Measures performance characteristics across compiler versions, enabling data-driven compiler optimization decisions.

Haskell Stellar SDK

Open-source Haskell client library for the Stellar blockchain network. First community SDK for Stellar in Haskell; used by DSTOQ in production.

More open-source work on GitHub.

Education

2001-2006

University "Ukraine"

Bachelor of Science in Computer Systems and Networks
1997-2001

Radio-Technical College

Junior Specialist in Computers Production and Servicing

Recommendations

Christopher Coffey
CTO @ CollegeVine
June 2019

When we extended our offer to Yuriy, he responded saying that CollegeVine's contract with Alan Turing was signed. While it turned out that this happened to be the name of the agency through which we were working, his sense of humor and zeal for writing quality software were apparent from day 1. Over the course of his time at CollegeVine Yuriy did very high-quality work. He made a major impact spinning up several new Haskell services from scratch, as well as several critical features in our UI. He was never afraid to venture into whichever part of the system we needed him in, and pretty much always left it better than he found it. He's been writing software for a long time, and that experience is apparent in Yuriy's ability to introduce positive change to teams. He was never afraid to share opinions and suggestions for improvement, most of which were adopted by the team. One particularly impressive bit of work was a property-based integration testing framework built upon Selenium, which we used to immediately protect a critical workflow for the company. If you're looking to start up a new engineering team or add a highly effective team member to an existing team, Yuriy is a great choice! I'd be thrilled to work with him again in the future.

Eric Torreborre
Senior Software Engineer (Rust, Haskell, Scala)
June 2019

I worked with Yuriy at Zalando, in the Merchant Operations department. You cannot make a mistake by deciding to work with Yuriy because he is curious, dedicated and very thorough. I was also the witness of Yuriy's growing love for Functional Programming, using various languages, like Haskell, Purescript, Scala and he is now a very skilled person in that domain, capable of delivering reliable and maintainable systems. On the personal side, he is pleasant to work with, always constructive and a team player. In one icon: highly recommended.

Patrice Moore
Full Stack Software Engineering Manager
February 2013

Yuriy was amazing. I have hired numerous developers, both in person and through odesk. Yuriy was one of the best. He started working on adding significant features, took responsibility for crafting solutions to technical issues with only minimal direction. Yuriy reachitected portions of FarReaches wordpress plugin to remove significant technical debt, created and improved significant parts of our automated testing framework, and created an eventbus that allows the browser javascript UI and the PHP wordpress plugin to communicate in an elegant, extensible manner.

Bartlomiej Nagorski
Delivery Manager & Job Family Lead at GFT
December 2012

Yuriy is highly proficient developer with extensive programming knowledge that covers development, testing and a huge number of frameworks and libraries. He is also familiar with different software development methodologies, which has proved to be very useful in his team lead role. Yuriy has been able to propose a number of technical solutions and process improvements to our clients, as well as organise work for the team and mentor his less experienced colleagues. I am recommending Yuriy, because he is a team player, a good colleague and an expert in software development.