When dealing with "hard bottoms", i.e. non-terminating computations that do not result in exceptions, the following functions may be handy.

Note that a computation is considered to have terminated when it has reached weak head normal form (i.e. something distinct from bottom).

timeOut n c runs c for at most n seconds (modulo scheduling issues).

• If the computation terminates before that, then Value v is returned, where v is the resulting value. Note that this value may be equal to bottom, e.g. if c = return Test.ChasingBottoms.IsBottom.bottom.
• If the computation does not terminate, then NonTermination is returned.
• If the computation raises an exception, then Exception e is returned, where e is the exception.

timeOut' is a variant which can be used for pure computations. The definition,

   timeOut' n = timeOut n . evaluate

ensures that timeOut' 1 Test.ChasingBottoms.IsBottom.bottom usually returns Exception <something>. (timeOut 1 (return Test.ChasingBottoms.IsBottom.bottom) usually returns Value Test.ChasingBottoms.IsBottom.bottom; in other words, the computation reaches whnf almost immediately, defeating the purpose of the time-out.)

timeOutMicro' is the equivalent variant of timeOutMicro:

  timeOutMicro' n = timeOutMicro n . evaluate