[Haskell-cafe] Syntax of 'do'

[Bulat Ziganshin]

Hello Mauri­cio,

Friday, August 29, 2008, 5:41:41 PM, you wrote:

afaik, this shorthand isn't exact. actually there is more code dealing
with fails and this code use Monad operations


> Hi,

> http://haskell.org/haskellwiki/Keywords says that:

> -------------
> [do is a] syntactic sugar for use with monadic
> expressions. For example:

>   do { x ; result <- y ; foo result }

> is shorthand for:

>   x >> y >>= \result -> foo result
> -------------

> I did some tests hiding Prelude.>> and Prelude.>>=
and applying >>> and >>= to non-monadic types, and
> saw that 'do' would not apply to them. So, I would
> like to add the following to that text:

> -------------
> as long as proper types apply:

> x :: Prelude.Monad a
> y :: Prelude.Monad b
foo :: b ->> Prelude.Monad c
> -------------

> Is that correct (Haskell and English)?

> Thanks,
> Mauricio

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-- 
Best regards,
 Bulat                            mailto:Bulat.Ziganshin at gmail.com