`Commit.S`

```
val make :
tree:hash ->
author:User.t ->
committer:User.t ->
?parents:hash list ->
?extra:(string * string list) list ->
string option ->
t
```

`make ~author ~committer ?parents ~tree msg`

makes an OCaml value `t`

. `?parents`

should be a non-empty list and corresponds to a list of hashes of parent commits. `tree`

should be a hash of a `Tree.t`

object.

**Note.** This function does not write a new commit on the store and does not check the validity of `parents`

and `tree`

. By this way, this function never fails.

`digest t`

associates a `hash`

to any value of `t`

. It is guaranteed that if `x = y`

or `compare x y = 0`

, then `digest x = digest y`

.

`val hash : t -> int`

`hash blob`

associates a non-negative integer to any value of `t`

. It is guaranteed that if `x = y`

or `compare x y = 0`

, then `hash x = hash y`

.

`val length : t -> int64`

`length t`

returns the length of the given commit object.

`val message : t -> string option`

`message c`

returns the message of the given commit object.

`val extra : t -> (string * string list) list`