2009/4/9 Mark Spezzano

Or does RT ignore the encapsulated data and just view the “action” performed by the monad as the “value” of the monad?

If I understand you right, this is more-or-less correct. You may as well think of IO as some sort of algebraic type that you are building and returning. A value of type "IO Integer" is not, itself, an integer. Thus: main = let r = print "hello" in return () Prints nothing. RT steps in in a similar scenario: main = let r = print "hello" in do { r; r } Replacing "r" with its definition: main = do { print "hello"; print "hello" } As expected. Luke

Just curious as to the rationale behind referential transparency and how it applies to monads.

Cheers,

Mark Spezzano

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