[Haskell-beginners] Pattern matching is actually about matching constructors??

[Kim-Ee Yeoh]

On Tue, Dec 22, 2015 at 1:56 AM, Olumide <50295 at web.de> wrote:

> Is the operator :-: a constructor? I'm confused because the definition of
> :-: is not prefixed by the data keyword?


The confusion is that the pattern-matching for append, i.e. (.++), is done
infix style:

Empty .++ ys = ys
(x :-: xs) .++ ys = x :-: (xs .++ ys)

This defines (.++).

It doesn't define (:-:).

The definition of (.++) pattern matches on (:-:) in (.++)-infix style to do
the job.

-- Kim-Ee
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