Announcing Lazy SmallCheck 0.1, a library for exhaustive, demand-driven testing of Haskell programs. Lazy SmallCheck is based on the idea that if a property holds for a partially-defined input then it must also hold for all fully-defined instantiations of that input. Compared to `eager' input generation in SmallCheck, Lazy SmallCheck may require significantly fewer test-cases to verify a property for all inputs up to a given depth. There is a webpage for Lazy SmallCheck: http://www-users.cs.york.ac.uk/~mfn/lazysmallcheck/ There you'll find a more detailed description, a worked example, a comparison with SmallCheck on a number of benchmarks, and link to download the library. The library was developed together with Fredrik Lindblad during his recent visits to York. Suggestions, experiences and bug reports are welcome! Matthew.