Hi, Thanks for bringing up these issues. It's something we could be better at addressing as a community. First, we need to stop pretending that you can use Haskell effectively without first learning to reason about program evaluation order. Learning how is not terrible difficult, but there's very little material on how to do it [1]. Some of us have learnt it the hard way by experimentation or by talking to people who do understand lazy evaluation [2] (the Simons, Don, and Bryan to name a few). At the very least we need to teach people how to tell which arguments a pure function is strict in by looking at its definition. Second, many of our core data structures are lazy, but most uses are strict. That keeping a simple map of counters is tricky should tell us that something is wrong (you need to use insertWith'). It wouldn't be if Data.Map was strict in the values. Many strictness related problems people have are due to common data types like Maybe, tuples, and arrays being lazy. This is rarely what you want. 1. I tried to start creating some. For example, by giving a high performance Haskell talk at CUFP. Unfortunately the talk wasn't taped. 2. Haskell is non-strict, which doesn't necessarily imply lazy evaluation. However, lazy evaluation is what we actually deal with. Johan