[Haskell-cafe] Referring to Prelude.(++)

Terry Hayes tdchayes at pacbell.net
Thu Sep 24 21:27:39 EDT 2009

Thanks, you got me to head in the correct direction.

I need to import Prelude twice, once without (++) and once qualified only for the (++) function.

  import Prelude hiding ( (++) )
  import qualified Prelude ( (++) )


From: Daniel Peebles <pumpkingod at gmail.com>
To: Terry Hayes <tdchayes at pacbell.net>
Cc: haskell-cafe at haskell.org
Sent: Thursday, September 24, 2009 6:02:18 PM
Subject: Re: [Haskell-cafe] Referring to Prelude.(++)

Did you try (Prelude.++)? I think that's the way it needs to be done.


On Thu, Sep 24, 2009 at 8:59 PM, Terry Hayes <tdchayes at pacbell.net> wrote:
> I'd like to redefine (++) so that it works on a more general class of
> "lists" (ListOf a).  To do this, I found that I can import the Prelude
> hiding the definition of (++).  Then I want to make [] an instance of
> ListOf, and have the (++) function call the built-in Prelude.(++).
> My problem is that I can't figure out how to call the built-in function.
> Just using "Prelude.(++)" doesn't seem to work in the way that
> "Prelude.foldl" would (for example).
> Any ideas?
> Terry
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> Haskell-Cafe at haskell.org
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