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| author |  Nickolai Zeldovich <nickolai@csail.mit.edu> | 2014-11-09 11:55:00 -0500 |
|---|---|---|
| committer |  Pierre Letouzey <pierre.letouzey@inria.fr> | 2015-04-09 12:33:51 +0200 |
| commit | 30446765297d79767b68e4a5f5b9160171b63b72 (patch) | |
| tree | 56b998c575dc3ea72171b93652b718a4b4e00500 /theories/Lists | |
| parent | 1688d4af1896effb42fa5dd191948795c59288a4 (diff) | |
Add a [map_ext_in] lemma to List.v.
Slightly broader version of the existing [map_ext]: two [map] expressions
are equal if their respective functions agree on all arguments that are
in the list being mapped.
Diffstat (limited to 'theories/Lists')
| -rw-r--r-- | theories/Lists/List.v | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/theories/Lists/List.v b/theories/Lists/List.v index 3cba090f3..00406f57d 100644 --- a/theories/Lists/List.v +++ b/theories/Lists/List.v @@ -1021,6 +1021,13 @@ Proof. rewrite H; rewrite IHl; auto. Qed. +Lemma map_ext_in : + forall (A B : Type)(f g:A->B) l, (forall a, In a l -> f a = g a) -> map f l = map g l. +Proof. + induction l; simpl; auto. + intros; rewrite H by intuition; rewrite IHl; auto. +Qed. + (************************************) (** Left-to-right iterator on lists *) |