leanprover / leanprover/reference-manual

Unify terminology around indexed families

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Description

What question should the reference manual answer?

From Zulip:

The concept referred to as an "inductive family" in TPiL seems to be called an "indexed family" in the language reference. I believe these refer to the same thing. Could you consider unifying the terminology? (This inconsistency in terminology has caused some confusion within the Japanese Lean community.)

TPiL: https://lean-lang.org/theorem_proving_in_lean4/inductive_types.html#inductive-families
Reference: https://lean-lang.org/doc/reference/latest//The-Type-System/Inductive-Types/#inductive-datatypes-parameters-and-indices

This is a useful thing to do.

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Research direction

Compare the terminology in the linked TPiL “inductive-families” section with the reference manual’s “Inductive datatypes: parameters and indices” section. Trace the surrounding reference-manual text for the same concept, then unify the naming consistently and verify that both sections no longer use conflicting terms.

Written by the indexing model from the issue text.

Assessment

Domain
documentation
Issue type
Documentation
Difficulty
2/5
Estimated time
1-3 hours
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
50/100

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