diff options
Diffstat (limited to 'src/Util/OptionList.v')
-rw-r--r-- | src/Util/OptionList.v | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/src/Util/OptionList.v b/src/Util/OptionList.v index c2157346e..4b88dd9a3 100644 --- a/src/Util/OptionList.v +++ b/src/Util/OptionList.v @@ -25,6 +25,11 @@ Module Option. | x :: xs => (x <- x; @bind_list A B xs (fun xs => f (x :: xs))) end%option%list. + Definition lift {A} (ls : list (option A)) : option (list A) + := fold_right (fun x xs => x <- x; xs <- xs; Some (x :: xs))%option + (Some nil) + ls. + Module Export Notations. Notation "A <-- X ; B" := (bind_list X (fun A => B%option)) : option_scope. End Notations. |