I noticed in the official style guide/NEP-1 there is no mention of how module names should be written, this should be changed.
Personal opinion: I like snake_case for modules, but compiler/std seems to do nocase
We use snake_case too, db_sqlite etc. You're right that the style checker should check this.
furthermore, a soft guideline would be to prefer plural in module name. This is often (but not always) the convention in stdlib, and it's a good one because it reduces name clashes (there are bugs related to this when module name matches proc name), makes things easier to search. eg:
And also, I suppose preferring nocase, but use snake_case for groups of modules with repetitive/common prefixes (such as db_* as Araq mentioned)
Most helpful comment
furthermore, a soft guideline would be to prefer plural in module name. This is often (but not always) the convention in stdlib, and it's a good one because it reduces name clashes (there are bugs related to this when module name matches proc name), makes things easier to search. eg: