Subject: Something like cat-file for the index?

Hi,

I'd like to have a more technical look into the index file and what/how it stores data; call it educational spelunking.

I know the index-format.txt but I'd really like to save me the work to implement a pretty-printed output based on it. I know ls-files but that's obviously not the whole thing.

So: is there something like cat-file, that basically gives me a readable
version of the information (version number and all...) in the index already
implemented or did nobody care until now?