status of mtl

Ben Franksen ben.franksen at
Thu Sep 30 09:36:30 UTC 2021

Am 30.09.21 um 10:01 schrieb Henning Thielemann:
> On Thu, 30 Sep 2021, Ben Franksen wrote:
>> The burden lies with those who want to use the new features: they need 
>> to convince other library maintainers to release compatibility updates 
>> with raised upper bounds on their mtl dependency, issuing PRs and 
>> lobbying for new releases. This is exactly as it should be.
> If I do not relax the version bounds of my Build-Depends on mtl then my 
> library gets outdated and other people who want to use new mtl features 
> are blocked by my library.

Indeed, that's the idea. If they want the new features badly enough, 
they will send PRs or patches. In most cases adjusting upper bounds in 
the cabal file is all that's needed, so pushing out a new patch release 
is a trivial matter that shouldn't take more than a few minutes of work.

> Actually, if a new major mtl version is released, then Stackage notifies 
> all transitively dependent packages and if authors do not update their 
> dependent libraries then the affected packages are kicked off from the 
> Stack package set.

Surely such notification is done far in advance of actually kicking off 
packages? Like, at least half, if not a full year? I would expect that 
stackage, as a curated set of packages with fixed versions, is expected 
to lag behind hackage for quite some time, trading access to the latest 
features for stability.

I would rather have questions that cannot be answered, than answers that
cannot be questioned.  -- Richard Feynman

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