For examples, check out the source tree, which in 0.9.2 contains these
examples:
./HAppS-HTTP/Examples/set/FromData/Cookies.hs
./HAppS-HTTP/Examples/set/FromData/Inline.hs
./HAppS-HTTP/Examples/set/FromData/Optional.hs
./HAppS-HTTP/Examples/set/FromData/Basics.hs
./HAppS-HTTP/Examples/set/ServerPart/PathSegments.hs
./HAppS-HTTP/Examples/set/ServerPart/SideEffects.hs
./HAppS-HTTP/Examples/set/ServerPart/HelloWorld.hs
./HAppS-HTTP/Examples/set/Web/FileServe.hs
./HAppS-HTTP/Examples/set/Web/ControlFlow.hs
./HAppS-HTTP/Examples/set/Web/Trace.hs
./HAppS-HTTP/Examples/set/Web/ErrorCodes.hs
./HAppS-HTTP/Examples/set/Web/IO.hs
./HAppS-HTTP/Examples/AllIn.hs
./HAppS-HTTP/Examples/Timer.hs
./HAppS-Data/examples/test.hs
./HAppS-Data/examples/Foo.hs
./HAppS-IxSet/Examples/IxState.hs
./HAppS-State/Examples/CheckpointTest.hs
./HAppS-State/Examples/testState.hs
For documentation, check out the examples. ;) Also see the happs.org site.
Given the limited documentation, the source code is pretty useful. E.g.
for understanding the URL dispatch mechanism, the code in SimpleHTTP.hs
in HAppS.Server is helpful.
Various people have blogged about using HAppS, sometimes in a tutorial
style. See e.g.:
http://reddit.com/r/programming/search?q=happs
If you come across articles elsewhere, note that HAppS has been evolving
pretty quickly, so older articles may be out of date.
Anton