Proposal for stand-alone deriving declarations?

Iavor Diatchki iavor.diatchki at
Thu Oct 5 13:58:47 EDT 2006

A question about the syntax:  would there be a problem if we made the
'deriving' declaration look like an instance?  Then we would not need
the special identifier 'for', and also we have a more standard looking
notation.  I am thinking something like:
deriving Show SomeType
deriving Eq (AnotherType a)

On 10/5/06, Björn Bringert <bringert at> wrote:
> Simon Peyton-Jones wrote:
> > | What is not so nice is that you take a new keyword ('for'), which is
> > | quite likely to have been used as a variable name in existing code.
> > (Or
> > | does it work out to use one of the 'special' names here?)
> >
> > The latter is what Bjorn has done.  That is, 'for' is only special in
> > this one context.  You can use it freely otherwise.  As I understand it
> > anyway.
> Yes. There is even a "for" function somewhere in the libraries (or was
> it the testsuite, can't remeber), which tripped up one of my early
> versions, before I had remembered to make "for" as a special ID in the
> parser.
> > | I think it would be useful to write the proposal in complete detail up
> > | on the Haskell' wiki.
> >
> > Yes please.  Bjorn?  (It may just be a qn of transcribing the user
> > manual stuff you have written.)
> Sure. It seems that I have to be on the committee to write to the Wiki.
> Can I join it?
> /Björn
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