split_extension path split the body and extension of path. split_extension "hello.world.txt" = "hello.world", ".txt" split_extension "hello_world" = "hello_world", ""

change_extension f ~ext changes the extension part of f. If f has no extension then change_extension f ~ext just attach ext to f.

change_extension "hello_world.txt" ~ext:".obj" = "hello_world.obj" change_extension "hello.world.txt" ~ext:".obj" = "hello.world.obj" change_extension "hello_world" ~ext:".obj" = "hello_world.obj" change_extension "hello_world" ~ext:"obj" = "hello_worldobj"

Note that change_extension does not check ext begins with '.' or not.

split_dir path splits path recursively using dirname and returns the list of directory and basename components of path.

split_dir "/a/b/c/d" = ["/"; "a"; "b"; "c"; "d"] split_dir "/a/b/c/d/" = ["/"; "a"; "b"; "c"; "d"] split_dir "a/b/c/d" = ["."; "a"; "b"; "c"; "d"]

split_dir "/a/b/./c/d" = ["/"; "a"; "b"; "."; "c"; "d"] split_dir "/a/b/../c/d" = ["/"; "a"; "b"; ".."; "c"; "d"] split_dir "../a/b/c/d" = ["."; ".."; "a"; "b"; "c"; "d"]

In Windows, split_dir "c:/a/b/c/d" = ["c:/"; "a"; "b"; "c"; "d"] split_dir "\\a\\b\\c\\d" = ["\\"; "a"; "b"; "c"; "d"]