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(* IMPORTS *)
(***********)
Require Import Coq.Arith.PeanoNat.
Require Import Coq.Lists.List.
Require Import Coq.Strings.String.
Require Import Coq.Strings.Ascii.

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(* strchr *)
(**********)
Fixpoint strchr (haystack : string) (needle : ascii) : string :=
  match haystack with
  | EmptyString => EmptyString
  | String c s' => match (Ascii.eqb needle c) with
                   | true => s
                   | false => strchr s' needle
                   end
  end.

(********************************)
(* Extraction Language: Haskell *)
(********************************)
Extraction Language Haskell.

(***************************)
(* Extract to Haskell file *)
(***************************)
Extraction "/home/oren/GIT/kMemLoops/strchr.hs" strchr.

Error: The reference Ascii.eqb was not found in the current environment.