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(* -*- coq-prog-args: ("-emacs-U" "-debug") -*- *)
Require Import JMeq.
Require Import List.
Require Import Coq.subtac.Utils.
Set Implicit Arguments.
Program Fixpoint take (A : Set) (l : list A) (n : nat | n <= length l) { struct l } : { l' : list A | length l' = n } :=
match n with
| 0 => nil
| S p =>
match l with
| cons hd tl => let rest := take tl p in cons hd rest
| nil => !
end
end.
Require Import Omega.
Next Obligation.
intros.
simpl in l0.
apply le_S_n ; exact l0.
Defined.
Next Obligation.
intros.
destruct_call take ; subtac_simpl.
Defined.
Next Obligation.
intros.
inversion l0.
Defined.
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