I think we have very different situations in our mind as we go bath and forth like this. It'd be fun to discuss this further over beer, but I think we've mostly hit the limit of what we can do in a HN thread. I'm picking the one major thing you said that I disagree with most:
> Your spell checking service shouldn't also be a translation service, and your translation service shouldn't also be a spell checking service.
I just want to stress how tremendously inflexible that is, and just how heavy of a decision you have to make any time you implement a new feature. This sounds like all the negatives of microservices (or DLL hell if that's your deployment model) with none of the positives. Boundaries are fuzzy! I have written a spell checker before. Later I needed an auto-complete service. Turns out: serendipity! I could implement auto-complete easily by simply implementing a separate error model that didn't take off points for "deletion errors" at the end of the word. And as a bonus, it was "fuzzy", so if you typed "Arnold Shwarz" it would suggest Schwarzenegger even though you missed the 'c'. The difference between the Spell Checking Service and the Fuzzy Autocomplete Service was one class of about 10 lines.
If you immediately set out with the mindset "your spell checking service shouldn't also be an autocomplete service" as if this is some sort of wisdom (it really, truly isn't), then you're hamstringing yourself from getting these kinds of easy wins. And maybe you decide autocomplete is close enough to spell-checking to warrant being in the same service, but your colleague might not, so now you needlessly argue over it. It shouldn't be a big decision! Just write it! So auto-complete goes in the service, but it's really close to feature X, which involves vectorizing words, which is the basis for a translation service. Now your spell checker is also a translation service. But what have we really lost? Who gives a crap that Wordsmith now has an extra feature? Nobody who was using its old features; they don't have to change at all.
> > I spent about 30 seconds coming up with "Wordsmith". It does something with words.
> Well, maybe until you're better at it, spend more time.
Needlessly nasty. Maybe I don't want to have a beer with you after all. Come on Wordsmith, I think you're beautiful just the way you are.
> If you immediately set out with the mindset "your spell checking service shouldn't also be an autocomplete service" as if this is some sort of wisdom (it really, truly isn't), then you're hamstringing yourself from getting these kinds of easy wins.
It's not "immediately setting out with a mindset", it's looking back on coming-up-on-2-decades of software development experience and noting that every time I think bolting a second responsibility onto a unit is an easy win, that decision comes back to bite me. It seems like an easy win now, but everything you change in that area of the code from now on needs to consider two different, disparate responsibilities it needs to maintain.
If you're seeing this as an easy win, it's likely that your software didn't see much use that played out the problems, or you didn't stick around long enough to see the problems arise, or someone else did the work to fix it and just didn't tell you.
> Nobody who was using its old features; they don't have to change at all.
Not yet, but if you assume they'll never have to change, you're going to have a bad time.
What's the longest you've ever worked on a codebase? Have you ever been the sole developer on a large codebase, where you had to pay for your own mistakes?
> Needlessly nasty. Maybe I don't want to have a beer with you after all
I don't think it was nasty at all. If you'd spent more than 30s on it you'd know that "wordsmith" already means "a skilled writer" and thus doesn't match the function of the tool you are describing. Names that appear to describe the function of a thing but don't are IMHO, the one of the worst kinds of bad names. You're better off with something that is either completely divorced from the underlying functionality or describes it correctly.
> Your spell checking service shouldn't also be a translation service, and your translation service shouldn't also be a spell checking service.
I just want to stress how tremendously inflexible that is, and just how heavy of a decision you have to make any time you implement a new feature. This sounds like all the negatives of microservices (or DLL hell if that's your deployment model) with none of the positives. Boundaries are fuzzy! I have written a spell checker before. Later I needed an auto-complete service. Turns out: serendipity! I could implement auto-complete easily by simply implementing a separate error model that didn't take off points for "deletion errors" at the end of the word. And as a bonus, it was "fuzzy", so if you typed "Arnold Shwarz" it would suggest Schwarzenegger even though you missed the 'c'. The difference between the Spell Checking Service and the Fuzzy Autocomplete Service was one class of about 10 lines.
If you immediately set out with the mindset "your spell checking service shouldn't also be an autocomplete service" as if this is some sort of wisdom (it really, truly isn't), then you're hamstringing yourself from getting these kinds of easy wins. And maybe you decide autocomplete is close enough to spell-checking to warrant being in the same service, but your colleague might not, so now you needlessly argue over it. It shouldn't be a big decision! Just write it! So auto-complete goes in the service, but it's really close to feature X, which involves vectorizing words, which is the basis for a translation service. Now your spell checker is also a translation service. But what have we really lost? Who gives a crap that Wordsmith now has an extra feature? Nobody who was using its old features; they don't have to change at all.
> > I spent about 30 seconds coming up with "Wordsmith". It does something with words.
> Well, maybe until you're better at it, spend more time.
Needlessly nasty. Maybe I don't want to have a beer with you after all. Come on Wordsmith, I think you're beautiful just the way you are.