Module Name Plugin: Treat modules starting with lowercase as Main module

[konn]

Currently, module name plugin treats basename of file as module name.
This inferes, for example, the module name of app/exe01.hs as exe01, contrary to the expectation that they must be Main.

This pull-requests addresses this issue by defaulting to Main when the file name is starting with non-upper cases.

Perhaps, the logic itself can be refined so that it infers it Main only when the lowercased file is located right after the source-dirs?

[jneira]

@konn thanks for the improvement. Is a main module the unique case where a module can start with lower case?

@tittoassini please, could you take a look?

[konn]

Is a main module the unique case where a module can start with lower case?

Well, strictly speaking, it could be different if it is specified with ghc option like -main-is NonStandardMain; without such options, modules starting with a lowercase must be treated as Main, IIRC.

At least, module names starting with a lowercase are rejected hence we should either provide a common default name for them or just stopping suggesting module names for them.

[jneira]

just stopping suggesting module names for them

The module header is optional for them, right? So it could be an alternative. However this pr is a improvement over the actual situation so imo it could be merged and only switch to a more defensive option if there is concrete real issues about.

[jneira]

LGTM, will merge soon if @tittoassini cant take a final look

[tittoassini]

Sorry for the delay in answering, the change seems perfectly legit to me.

(Un)related question:

Most of the changes in the commit are 'noise' due to differences in the formatting of the import statements.

Is there a project-wide standard for formatting?

[jneira]

@tittoassini

Is there a project-wide standard for formatting?

I am afraid it is not.

It is a somewhat tricky question, as afaik almost each dev has a favourite formatting flavour 😝
In general we suggest to not make those changes and respect the formatting of each file in the hope some day someone will do the titanic effort to apply a formatter to all codebase, to start following it.

But personally i am not very strict about, as this pr demonstrates 😄