Which stable GHC release is expected to have support for linear types?

Wolfgang Jeltsch wolfgang-it at jeltsch.info
Wed Jul 12 20:47:45 UTC 2017

Am Mittwoch, den 12.07.2017, 16:15 -0400 schrieb Brandon Allbery:
> On Wed, Jul 12, 2017 at 4:11 PM, Wolfgang Jeltsch 
> .info> wrote:
> > I had thought about this possibility already, but then concluded
> > that this was not the case, since types of the form a -o b were not
> > supported. However, when looking at the diffs, I discovered that at
> > the moment, only the Unicode syntax a ⊸ b is understood.
> "-o" is going to give the lexer fits. Come up with a purely symbolic
> version.
It was not me who invented the syntax “-o”. Actually, I do not like it
either. While it nicely resembles the lollipop (⊸), implementing it
requires stealing syntax. This syntax stealing is worse than the syntax
stealing of, say, hierarchical modules. With hierarchical modules in
place, you have to use spaces in function composition, but this is
reasonable anyhow. However, with “-o” as a lollipop alternative in
place, you have to write the negation of o with a space, which is
Alternatives for “-o” I can think of are “~>”, “-:”, and “-*”, the
latter resembling the magic wand operators in the logic of bunched
implications and in separation logic, which are similar to the lollipop
in linear logic.
All the best,
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