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(** Extraction of [Z] into Haskell's [Integer] *)
From Stdlib Require Extraction.
From Stdlib Require Import ZArith.
From Stdlib Require Import ExtrHaskellZNum.
(** Disclaimer: trying to obtain efficient certified programs
by extracting [Z] into [Integer] isn't necessarily a good idea.
See comments in [ExtrOcamlNatInt.v].
*)
Extract Inductive positive => "Prelude.Integer" [
"(\x -> 2 Prelude.* x Prelude.+ 1)"
"(\x -> 2 Prelude.* x)"
"1" ]
"(\fI fO fH n -> if n Prelude.== 1 then fH () else
if Prelude.odd n
then fI (n `Prelude.div` 2)
else fO (n `Prelude.div` 2))".
Extract Inductive Z => "Prelude.Integer" [ "0" "(\x -> x)" "Prelude.negate" ]
"(\fO fP fN n -> if n Prelude.== 0 then fO () else
if n Prelude.> 0 then fP n else
fN (Prelude.negate n))".
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