Like "Monad" seems to be strongly attached to Haskell and the writings of Wadler. Never seen "Monad" in CAML code. Monadic programming is indeed very convenient in Haskell, thanks to type classes. It is certainly possible in ML, for example, http://groups.google.com/groups?selm=r8td785em7f.fsf%40chinstrap.CS.Princeton.EDU You can program monadically even in Unix shell! It is rather common, actually. Everybody who piped "echo" or "cat" into another program did monadic programming! http://pobox.com/~oleg/ftp/Computation/monadic-shell.html Monads seem to have a parallel in Scheme closures, but I've never seen anyone make this analogy. Monadic programming is closely related to "staging." You first write code (a "compiler") that creates a sequence of "commands". Afterwards, you execute the commands. The two passes are apparent. The command executor is a strict evaluator (whereas the evaluator that creates a "command stream" may be lazy). To achieve such staging in Scheme -- i.e., to create a "command" to be evaluated later -- you typically wrap it into a closure (or use 'delay' to make it a promise). Any "instruction" stream can be regarded as a "monad", providing the stream is associative and the instruction set contains a no-op "instruction" that can be dropped from the instruction stream with impunity. see also the third paragraph of
http://groups.google.com/groups?selm=8d8kd2%24sr4%241%40nnrp1.deja.com 
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Category theory for non-mathematicians