4f664fb3b5
Complement to #3967 , adds a `(since := "<date>")` field to `@[deprecated]` so that metaprogramming code has access to the deprecation date for e.g. bulk removals. Also adds `@[deprecated "deprecation message"]` to optionally replace the default text "`{declName}` has been deprecated, use `{newName}` instead".
25 lines
577 B
Text
25 lines
577 B
Text
/- Well-founded recursion -/
|
|
|
|
def ack : Nat → Nat → Nat
|
|
| 0, y => y+1
|
|
| x+1, 0 => ack x 1
|
|
| x+1, y+1 => ack x (ack (x+1) y)
|
|
termination_by x y => (x, y)
|
|
|
|
def sum (a : Array Int) : Int :=
|
|
let rec go (i : Nat) :=
|
|
if _ : i < a.size then
|
|
a[i] + go (i+1)
|
|
else
|
|
0
|
|
termination_by a.size - i
|
|
go 0
|
|
|
|
set_option pp.proofs true
|
|
#print sum.go
|
|
/-
|
|
def sum.go : Array Int → Nat → Int :=
|
|
fun a =>
|
|
WellFounded.fix (sum.go.proof_1 a) fun i a_1 =>
|
|
if h : i < Array.size a then Array.getOp a i + a_1 (i + 1) (sum.go.proof_2 a i h) else 0
|
|
-/
|