Backwards arrow direction

Is your feature request related to a problem? Please describe. Sometimes it is useful to have a single arrow pointing in the opposite direction (and not the whole graph).

Describe the solution you’d like Simply the option to specify the backwards arrow (like <--).

Describe alternatives you’ve considered You can try to do something similar using subgraphs, but it is very cumbersome (and not really comparable).

Additional context In Graphviz they do using the dir attribute ([dir=back]).

[ajh0912]

An example with flowchart

flowchart LR
%% Currently have to use no arrows
A <--> B --- C

%% Proposed syntax to allow left arrow
%% D <--> E <-- F

flowchart LR
%% Currently have to use no arrows
A <--> B --- C

%% Proposed syntax to allow left arrow
%% D <--> E <-- F

mermaid.live link

Proposed render:

[daniporr]

@daniporr could you please add an example with current behaviour (simple code and rendered image) and maybe an assumed code with a sketch of changed version? It would help with an implementation and quick testing I think

The point is exactly that you cannot achieve that.

Assume you have this graph:

graph TD
    A --> B

And now you want to add a new node C and an edge from B to C with the arrow pointing to B.

You could do something like this:

graph TD
    A --> B
    C --> B

But this puts C at “the same level” of A, but here you are interested in having an edge from B to C just with the arrow in the opposite direction. Something like this: (which obviously does not compile at the moment)

graph TD
    A --> B
    B <-- C

Just to show something, it should be like this one:

graph TD
    A --> B
    B --- C

but with an arrow on the B -- C edge pointing towards B (exactly how @ajh0912 has shown in https://github.com/mermaid-js/mermaid/issues/3208#issuecomment-1267495095).

@mitcom is this small example clear enough?