Skip to content

feat(naming): update naming conventions for Prop-valued classes #882

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
fpvandoorn merged 2 commits into from
Jul 17, 2026
Merged

feat(naming): update naming conventions for Prop-valued classes #882

Changes from 1 commit
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
1f8f3a0
feat(naming): update naming conventions for Prop-valued classes
fpvandoorn Jun 22, 2026
5a8aa65
fix
fpvandoorn Jun 22, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
7 changes: 6 additions & 1 deletion templates/contribute/naming.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -525,13 +525,18 @@ and "let $G$ be a group and let $H$ be a normal subgroup" is written
and `Normal H` are not extra data, but are extra assumptions on data we have already.

Mathlib currently strives towards the following naming convention for these `Prop`-valued
classes. If the class is a noun then its name should begin with `Is`. If however is it an adjective
classes. If the class is a noun (or noun phrase) then its name should begin with `Is`. If however is it an adjective
then its name does not need to begin with an `Is`. So for example `IsNormal` would be acceptable
for the "normal subgroup" typeclass, but `Normal` is also fine; we might say "assume the subgroup
`H` is normal" in informal language. However `IsTopologicalRing` is
preferred for the "topological ring" typeclass, as we do not say "assume the ring `R` is
topological" informally.

If the predicate is referring to data other than the explicit argument,
then the prefix `Has` may be used instead of the prefix `Is`.
Examples: `Filter.HasBasis`, `Function.HasLeftInverse`, `HasLimit` (for a functor in category theory),
`HasCompactSupport` (`IsCompactlySupportedFunction` would also follow this naming scheme, but is very long).

### Unexpanded and expanded forms of functions

The multiplication of two functions `f` and `g` can be denoted equivalently as
Expand Down
Loading