606aeddf06
This PR changes how generalized field notation ("dot notation") resolves
the function. The new resolution rule is that if `x : S`, then `x.f`
resolves the name `S.f` relative to the root namespace (hence it now
affected by `export` and `open`). Breaking change: aliases now resolve
differently. Before, if `x : S`, and if `S.f` is an alias for `S'.f`,
then `x.f` would use `S'.f` and look for an argument of type `S'`. Now,
it looks for an argument of type `S`, which is more generally useful
behavior. Code making use of the old behavior should consider defining
`S` or `S'` in terms of the other, since dot notation can unfold
definitions during resolution.
This also fixes a bug in explicit-mode generalized field notation
(`@x.f`) where `x` could be passed as the wrong argument. This was not a
bug for explicit-mode structure projections.
Closes #3031. Addresses the `Function` namespace issue in #1629.
54 lines
1.2 KiB
Text
54 lines
1.2 KiB
Text
/-- A `Vec` is just a `List α` of statically known size -/
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def Vec (α : Type _) (n : Nat) : Type _
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:= Fin n → α
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abbrev TypeVec : Nat → Type _
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:= Vec (Type _)
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/-- A dependent vector is a heterogeneous list of statically known size -/
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def DVec {n : Nat} (αs : TypeVec n) : Type _
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:= (i : Fin n) → (αs i)
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/-- A vector that repeats a single element `a` -/
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def Vec.const {α : Type _} (a : α) (n : Nat) : Vec α n
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:= fun _ => a
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/- `Vec` is defeq to a `DVec` with constant type -/
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unif_hint (α : Type _) (n : Nat) where
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|- Vec α n =?= DVec (Vec.const α n)
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namespace DVec
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def hd {n : Nat} {αs : TypeVec (n+1)} (v : DVec αs) : (αs 0)
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:= v 0
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end DVec
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namespace Vec
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export DVec (hd)
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end Vec
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def ts : TypeVec 1 := Vec.const Nat 1
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-- works
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example (v : DVec ts) : Nat :=
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v.hd
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-- works
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example (v : Vec Nat 1) : Nat :=
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DVec.hd v
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#check @Vec.hd
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-- Does not work: Aliases find that `v` could be the `TypeVec` argument since `TypeVec` is an abbrev for `Vec`.
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/--
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error: application type mismatch
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@Vec.hd ?_ v
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argument
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v
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has type
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Vec Nat 1 : Type
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but is expected to have type
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TypeVec (?_ + 1) : Type (_ + 1)
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-/
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#guard_msgs in set_option pp.mvars false in
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example (v : Vec Nat 1) : Nat :=
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v.hd
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