An action in this sense is just a function of type `Monad m => a -> m b'
(or one where the monad is specified, like `a -> IO b'). This type
signature fully specifies the "formal properties" of an action and shows
that actions do not differ from functions: they are merely functions of a
certain type.
On Sat, Oct 19, 2013 at 3:23 PM, Brandon Allbery
On Sat, Oct 19, 2013 at 5:09 PM, MJ Williams < matthewjwilliams101@gmail.com> wrote:
For example, `main = do input <- getLine ...', where `getLine' is an action as distinguished from a function such as `main'. Other examples of actions in Haskell include `print', `putStrLn' and
Actions aren't so much a formal thing as a conceptual "handle" to help with understanding monads. In particular, what a particular action represents depends on the monad, and in some cases on the particular implementation (for example, an IO action in GHC is a partially applied function, but this is an implementation detail that does nothing to help you understand how to work with it).
-- brandon s allbery kf8nh sine nomine associates allbery.b@gmail.com ballbery@sinenomine.net unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net
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