Composition operator [was: Re: Records in Haskell]

Greg Weber greg at
Thu Jan 12 22:29:31 CET 2012

On Thu, Jan 12, 2012 at 6:23 PM, Malcolm Wallace <malcolm.wallace at>wrote:

> On 12 Jan 2012, at 18:41, Evan Laforge wrote:
> >>> Unicode dot (∘) would be optimal, since that's what it's for.
> >>
> >> Is ∘ (U+2218 RING OPERATOR)* in Prelude yet? We should propose that.**
> >
> > However, changing the composition operator from (.) will involve huge
> > amounts of changes to source code.
> Indeed.  It strikes me that it should be the _new_ feature that takes the
> new syntax, rather than stealing the old syntax and disrupting all the
> existing code that happily uses . for function composition.
> So, who is up for proposing centred dot as the new record-field syntax?

We don't need to make this change overnight. The new records system will be
turned on by an extension. If you use the new records system, then you will
be forced to place spaces around the dot composition operator, or use the
unicode dot or an alternative operator.

It is good that we are starting this process of discussing what the future
should look like though.
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