Is there anyway to keep comments while extracting Coq to Haskell? Ideally, I would like to have machine generated Haskell files untouched by humans, and so the motivation of extracting comments is clear. However, I couldn't find how to do it, and I wonder if this is at all possible (?). Here is an example Coq file:
(*************)
(* factorial *)
(*************)
Fixpoint factorial (n : nat) : nat :=
match n with
| 0 => 1
| 1 => 1 (* this case is redundant *)
| S n' => (mult n (factorial n'))
end.
Compute (factorial 7).
(********************************)
(* Extraction Language: Haskell *)
(********************************)
Extraction Language Haskell.
(***************************)
(* Extract to Haskell file *)
(***************************)
Extraction "/home/oren/Downloads/RPRP/output.hs" factorial.
And when I extract it to Haskell everything works fine other than the fact that the comment inside factorial is lost:
$ coqc ./input.v > /dev/null
$ cat ./output.hs
module Output where
import qualified Prelude
data Nat =
O
| S Nat
add :: Nat -> Nat -> Nat
add n m =
case n of {
O -> m;
S p -> S (add p m)}
mul :: Nat -> Nat -> Nat
mul n m =
case n of {
O -> O;
S p -> add m (mul p m)}
factorial :: Nat -> Nat
factorial n =
case n of {
O -> S O;
S n' ->
case n' of {
O -> S O;
S _ -> mul n (factorial n')}}
