lean2/tests/lean/run/subst_test2.lean

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2015-05-26 00:02:23 +00:00
import data.nat
open nat
structure less_than (n : nat) := (val : nat) (lt : val < n)
namespace less_than
open decidable
set_option pp.beta false
definition less_than.has_decidable_eq [instance] (n : nat) : ∀ (i j : less_than n), decidable (i = j)
| (mk ival ilt) (mk jval jlt) :=
match nat.has_decidable_eq ival jval with
| inl veq := inl (by substvars)
| inr vne := inr (by intro h; injection h; contradiction)
end
end less_than