[Haskell] Evil code

[Albert Lai]

Thomas Davie <tom.davie at gmail.com> writes:

> The evil code and CPSness were actually intended to be completely
> separate entities.  I needed (and to a lesser extent now still need),
> examples that are (a) very higher order, and (b) evil and hard to
> understand the runtime behaviour of.

Generally code that produces and consumes lots of tuples, e.g., common
implementations of splitAt, span, mapAccumL (these are list
functions), the State monad (Control.Monad.State; you can strip out
the "instance Monad" thing and package the code as ordinary
functions).

Also Phil Wadler's "Monads for Functional Programming"
http://homepages.inf.ed.ac.uk/wadler/topics/monads.html#marktoberdorf
contains a monadic parser.  In section 5.11 "improving laziness" two
different ways of coding and their respective laziness effects are
shown.  This can be further exemplified by debugger traces, methinks.