Generating fresh names in a source plugin

[Simon Peyton Jones]

Ugh.  I realise that you were talking about *source* plugins, which work in
the Hsc monad, which indeed has no obvious way to generate uniques.

I have created https://gitlab.haskell.org/ghc/ghc/-/issues/26264 to
document my learning journey.

Simon



On Mon, 4 Aug 2025 at 11:44, Simon Peyton Jones <simon.peytonjones at gmail.com>
wrote:

> What about calling this function?
>
> GHC.Tc.Plugin.newUnique :: TcPluginM Unique
>
> The module GHC.Tc.Plugin provides facilities to plugins.
>
> More generally, here is the manual page for plugins
> <https://ghc.gitlab.haskell.org/ghc/doc/users_guide/extending_ghc.html#compiler-plugins>.
> Is it adequate?
>
> I notice that
>
>    - it mentions the module GHC.Plugins (but only in code fragments)
>    - it does not mention GHC.Tc.Plugins; neither does GHC.Plugins
>    re-export GHC.Tc.Plugins
>
> It would be great if some plugin authors felt able to offer patches to
> improve.  Maybe open a GHC ticket?
>
> Simon
>
>
>
> On Sat, 2 Aug 2025 at 14:16, Wolfgang Jeltsch <wolfgang at well-typed.com>
> wrote:
>
>> [Since it seems that `glasgow-haskell-users at haskell.org` is essentially
>> an announcements-only mailing list these days, I’m re-sending my recent
>> e-mail to that mailing list here.]
>>
>> Hello!
>>
>> I want to generate AST fragments in a source plugin, and for this I need
>> to generate fresh (local) names. My current approach is to use
>> `mkSystemName`, but it, like many of the other name-generating
>> operations, needs a value of type `Unique`. How can I generate such
>> values? It seems that the `Hsc` monad doesn’t carry a value of type
>> `UniqueSupply` with it.
>>
>> All the best,
>> Wolfgang
>> _______________________________________________
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>> ghc-devs at haskell.org
>> http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs
>>
>
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