dependency tree display

[Vick Khera]

Is there a way to visualize the dependencies of a port in a tree-like
fashion? That is, if A depends on B, and B depends on C, show me A -> B ->
C.

When I upgrade something in node using npm, it gives this kind of nice tree:

hal at 2.0.0 /u/lorax1/home/hubot/hal
├─┬ aws2js at 0.8.3
│ └─┬ libxml-to-js at 0.3.11
│   └─┬ libxmljs at 0.18.4
│     └─┬ node-pre-gyp at 0.6.33
│       └── request at 2.80.0
├── hubot-jira-commands at 1.1.0  (git://
github.com/khera/hubot-jira-commands.git#20b8792eeecf9cbdc1c36462fd42c44cdf7e926b
)
├─┬ hubot-s3-brain at 0.1.0
│ └── aws-sdk at 2.28.0
└─┬ hubot-slack at 4.3.3
  └─┬ @slack/client at 3.8.1
    ├─┬ https-proxy-agent at 1.0.0
    │ └── debug at 2.6.3
    ├─┬ request at 2.81.0
    │ ├─┬ har-validator at 4.2.1
    │ │ └── ajv at 4.11.5
    │ ├─┬ http-signature at 1.1.1
    │ │ └─┬ jsprim at 1.4.0
    │ │   └── assert-plus at 1.0.0
    │ ├── qs at 6.4.0
    │ ├── safe-buffer at 5.0.1
    │ └── tunnel-agent at 0.6.0
    └── ws at 1.1.4

It would be so awesome to be able to see that for freebsd ports as well. I
was thinking that poudriere might be a good tool to start from, since it
has to build this dependency tree internally already. I think it would make
a great report to get out of pkg version as well to show existing installed
dependencies.

Has anyone built anything like this yet?