[Haskell-cafe] How to make boolean logic with IO Monad more expressive?

[Magicloud Magiclouds]

Good call. I see `orM` is actually a wrapper of the "ugly" nested-if.
So operators can be another wrapper away. Thanks.

On Mon, May 27, 2019 at 3:35 PM Emil Axelsson <78emil at gmail.com> wrote:
>
> Not with the standard `||` and `&&` operations. You'd have to define new
> versions with a `Monad` constraint.
>
> The `monad-loops` package is pretty nice for short-circuiting stuff.
> See, for example, `andM` and `orM`. But it doesn't provide any binary
> operators.
>
> https://hackage.haskell.org/package/monad-loops
>
> / Emil
>
> Den 2019-05-27 kl. 07:07, skrev Magicloud Magiclouds:
> > Hi,
> >
> > I think `a || b && c` is more clear than
> > ```
> > if a
> >    then True
> >    else if b
> >      then if c
> >        then True
> >        else False
> >      else False
> > ```
> >
> > And some languages, `pureComputing || (ioOperation && pure2)` involves
> > IO only when pureComputing is False.
> >
> > So in Haskell, is it possible to get both benefits?
> > ```
> > status <- ioOperation -- IO-ed anyway
> > return $ pureComputing || (status && pure2)
> > ```
> > ```
> > if pureComputing
> >    then return True
> >    else do
> >      status <- ioOperation
> >      if status
> >        then return pure2
> >        else return False
> > -- Looks ugly
> > ```
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