Re: [Haskell-cafe] nested function application question

5 Jan 2009

      On Mon, Jan 5, 2009 at 3:16 PM, Brandon S. Allbery KF8NH
 wrote:
...
On 2009 Jan 5, at 13:57, David Menendez wrote:
...
2009/1/5 Ross Mellgren :
...
If for some reason you absolutely need to avoid parentheses (mostly as a
thought exercise, I guess), you'd have to have a flipped version of
intercalate:
Or a version of ($) that associates differently.
infixl 0 $$
f $$ x = f x
*Main Data.ByteString> :t \x y z -> intercalate $$ intercalate x y $$ z
\x y z -> intercalate $$ intercalate x y $$ z :: ByteString
                                               -> [ByteString]
                                               -> [ByteString]
                                               -> ByteString
...at which point we're reinventing Applicative, no?
Is "const" a reinvention of "return"?

You could write the above code with (<*>), but you'd need to convert
back and forth from Identity in order to get the proper Applicative
instance.

    runIdentity $ Identity B.intercalate <*> Identity (B.intercalate x
y) <*> Identity z

At that point, you might as well save the noise and write,

    B.intercalate (B.intercalate x y) z

-- 
Dave Menendez 
http://www.eyrie.org/~zednenem/