This PR changes the signature of `Array.get` to take a Nat and a proof,
rather than a `Fin`, for consistency with the rest of the (planned)
Array API. Note that because of bootstrapping issues we can't provide
`get_elem_tactic` as an autoparameter for the proof. As users will
mostly use the `xs[i]` notation provided by `GetElem`, this hopefully
isn't a problem.
We may restore `Fin` based versions, either here or downstream, as
needed, but they won't be the "main" functions.
---------
Co-authored-by: David Thrane Christiansen <david@davidchristiansen.dk>
This reverts commit 706a4cfd73 introduced
in #3970
As explained in #4124, `findM?` can become a footgun if used in monads
which induce side-effects such as caching. This PR removes that
function, and fixes the code introduced by #3398 for which the function
was first added.
cc @semorrison.
Closes#3386
Currently, when generating the signature of an injectivity lemma for a
certain constructor `c : forall xs, Foo a_1 ... a_n`,
`mkInjectiveTheoremTypeCore?` will differentiate between variables which
are bound to stay the same between the two equal values (i.e inductive
indices), and non-fixed ones. To do that, the function currently checks
whether a variable `x ∈ xs` appears in the final co-domain `Foo a_1 ...
a_n` of the constructor. This condition isn't enough however. As shown
in the linked issue, the codomain may also depend on variables which
appears in the type of free vars contained in `Foo a_1 ... a_n`, but not
in the term itself. This PR fixes the issue by also checking the types
of any free variable occuring in the final codomain, so as to ensure
injectivity lemmas are well-typed.
