Live language examples
Real .lasso pages execute arrays, custom tags, request parameters, encoding, dates, and control flow on this worker.
A living home for legacy Lasso
Lasso 8.6 applications,
running again.
Lairu Legacy is a clean-room interpreter written in Rust for trusted applications built against the final Lasso 8 generation. It preserves the language people wrote—not the retired server around it.
1,572documented contracts
1,523implemented behaviors
49explicitly unavailable
8.6one production profile
Introduction
Compatibility without pretending it is 2009
Lasso sites often contain years of domain knowledge in a compact mixture of HTML, square tags, LassoScript, custom types, database actions, sessions, and framework conventions. Rewriting all of that at once is risky. Lairu Legacy provides a controlled path: run the old application on a maintainable runtime, put it behind a current web server, and migrate on your own schedule.
The target is deliberately narrow. Lasso 8.6 is treated as the production release, and every feature documented for 8.5 is part of that 8.6 profile. A worker builds that feature registry once when it starts; requests do not pay for version selection or rebuild compatibility tables.
What is here
Evidence before claims
Framework applications
Request-driven fixtures and demo apps exercise PageBlocks, LassoFusebox/LFB, and the latest recovered Knop 8 source.
See framework gates →Feature-by-feature ledger
Every recovered 8.5/8.6 contract has a semantic test and a published implementation state.
Browse the ledger →The operating principle
Preserve observable application behavior. Replace the proprietary host, administration layer, and obsolete deployment assumptions with explicit modern boundaries.