recursion - How to unfold a recursive function just once in Coq -



recursion - How to unfold a recursive function just once in Coq -

here recursive function all_zero checks whether members of list of natural numbers zero:

require import lists.list. require import basics. fixpoint all_zero ( l : list nat ) : bool := match l | nil => true | n :: l' => andb ( beq_nat n 0 ) ( all_zero l' ) end.

now, suppose had next goal

true = all_zero (n :: l')

and wanted utilize unfold tactic transform to

true = andb ( beq_nat n 0 ) ( all_zero l' )

unfortunately, can't simple unfold all_zero because tactic eagerly find , replace instances of all_zero, including 1 in once-unfolded form, , turns mess. there way avoid , unfold recursive function once?

i know can accomplish same results proving advertisement hoc equivalence assert (...) x, inefficient. i'd know if there's easy way similar unfold.

it seems me simpl want. if have more complicated goal, functions want apply , functions want maintain are, might need utilize various options of cbv tactic (see http://coq.inria.fr/distrib/current/refman/reference-manual010.html#hevea_tactic127).

recursion coq unfold

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