This is a library of interactive processes combinators, usable to define extensible keymaps.

(Inspired by the Parsec library, written by Koen Claessen)

The processes are:

• composable: in parallel using <|>, in sequence using monadic bind.
• extensible: it is always possible to override a behaviour by combination of adjustPriority and <|>. (See also <|| for a convenient combination of the two.)
• monadic: sequencing is done via monadic bind. (leveraging the whole battery of monadic tools that Haskell provides)

The processes can parse input, and write output that depends on it.

The semantics are quite obvious; only disjunction deserve a bit more explanation:

in p = (a <|> b), what happens if a and b recognize the same input (prefix), but produce conflicting output?

• if the output is the same (as by the PEq class), then the processes (prefixes) are merged * if a Write is more prioritized than the other, the one with low priority will be discarded * otherwise, the output will be delayed until one of the branches can be discarded. * if there is no way to disambiguate, then no output will be generated anymore. This situation can be detected by using possibleActions however.