lean4-htt/tests/lean/run/missingSizeOfArrayGetThm.lean
Kim Morrison 3a408e0e54
feat: change Array.get to take a Nat and a proof (#6032)
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>
2024-11-12 03:30:46 +00:00

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inductive Node (Data : Type) : Type where
| empty : Node Data
| node (children : Array (Node Data)) : Node Data
| leaf (data : Data) : Node Data
def Node.FixedBranching (n : Nat) : Node Data → Prop
| empty => True
| node children => children.size = n ∧ ∀ (i : Nat) h, (children[i]'h).FixedBranching n
| leaf _ => True
structure MNode (Data : Type) (m : Nat) where
node : Node Data
fix_branching : node.FixedBranching m