[Haskell-cafe] [] vs [()]

[Jonathan Cast]

On Fri, 2008-10-10 at 10:59 -0700, Daryoush Mehrtash wrote:
> I was in fact trying to figure out how "guard" worked in the "do".
> The interesting  (for a beginner) insight is that: 
> 
>         [()]  map f = [f]

I don't think any clarity is added by made-up notation.  I think you
mean

  map f [()] = [f ()]

or

  [()] >>= f = f ()

or

  [()] >> f = f

or

  do
     [()]
     f
= f

or

  [ f | _ <- [()] ] = [ f ]

>           --( just as any list with one element would have been such
>         as [1] map f = [f] )   where as
>         
>         [] map f = []

And

  map f [] = []

or

  [] >>= f = []

or

  [] >> f = []

or

  do
     []
     f
= []

or

  [ f | _ <- [] ] = []

jcc