e9a318df16
This PR rewords the "application type mismatch" error message so that the argument and its type precede the application expression.
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: The argument
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v
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has type
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Vec Nat 1
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of sort `Type` but is expected to have type
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TypeVec (?_ + 1)
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of sort `Type (_ + 1)` in the application
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@DVec.hd ?_ v
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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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