Discovering scala-cli while fixing my digital photo archive

Over the years I built up a nice digital photo library with my family. It is a messy process. Here are some of the things that can go wrong:

• Digital cameras that add incompatible exif metadata.
• Some files have exif tag CreateDate, others DateTimeOriginal.
• Images shared via Whatsapp or Signal do not have an exif date tag at all.
• Wrong rotation.
• Fuzzy, yet memorable jpeg images wich take 15MB because of their resolution and high quality settings.
• Badly supported ancient movie formats like 3gp and RIFF AVI.
• Old movie formats that need 3 times more disk space than h.265.
• Losing almost all your photos because you thought you could copy an Iphoto library using tar and cp (hint: you can’t). (This took a low-level harddisk scan and months of manual de-duplication work to recover the photos.)
• Another low-level scan of an SD card to find accidentally deleted photos.
• Date in image file name corresponds to import date, not creation date.
• Weird file names that order the files differently than from creation date.
• Images from 2015 are stored in the folder for 2009.
• etc.

I wrote countless bash scripts to mold the collection into order. Unfortunately, to various success. However, now that I am ready to import the library into Immich (please, do sponsor them, they are building a very nice product!), I decided to start cleaning up everything.

So there I was, writing yet another bash script, struggling with parsing a date response from exiftool. And then I remembered the recent articles about scala-cli and decided to try it out.

The experience was amazing! Even without proper IDE support, I was able to crank out scripts that did more, more accurately and faster than I could ever have accomplished in bash.

Here are some of the things that I learned:

• Take the time to learn os-lib.
• If the scala code gets harder to write, open a proper IDE and use code completion. Then copy the code over to your .sc file.
• One well placed .par (using scala-parallel-collections) can more than quadruple the performance of your script!
• You will still spend a lot of time parsing the output from other programs (like exiftoool).
• Scala-cli scripts run very well from Github actions as well.

Conclusions

Next time you open your editor to write a bash file, think again. Perhaps you should really write some scala instead.