[Haskell-cafe] IO (Either a Error) question

[Eugene Dzhurinsky]

On Wed, May 05, 2010 at 02:54:27PM -0700, Ryan Ingram wrote:
> ErrorT is just a newtype wrapper, changing the order/application of
> the type variables.
> 
> newtype ErrorT e m a = ErrorT (m (Either e a))
> runErrorT (ErrorT action) = action
> 
> This gives the bijection:
> 
> ErrorT :: m (Either e a) -> ErrorT e m a
> runErrorT :: ErrorT e m a -> m (Either e a)

That syntax is not clear for me - so ErrorT is some sort of function
(calculation), which takes a monad with type (Either e a) and produces type
ErrorT e m a ? Basically, i don't understand what does "ErrorT ::" means - it
should name the function - but it starts with capital letter?

I feel like I missed something when learning type system and syntax of Haskell
:(

-- 
Eugene N Dzhurinsky
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