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Structs are mostly enforced at compile time. They save you from a part of errors you’d otherwise get at runtime.
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Structs blow up at runtime if you touch them the wrong way (as your colleague did). And they give you a very clear error message.
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Structs convey the message that you really want a certain piece of data to be shaped this way or that way. A good programmer will stop and think “why do they disallow removing of keys from this thing?” and maybe go and ask their colleague in charge of that code – this fosters communication in the team which is always a good thing.
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Structs will slap you on the wrists if you introduce a new field and make it mandatory (the
@enforce_keys [:field_a, :field_b, ...]annotation just above thedefstructexpression) and you’ll have an exact list of compile errors to work through, which accelerates your work (as opposed to getting paranoid and adding more and more tests which might not even catch the problems that can come into existence by introducing the new field).
The benefits are practical and numerous but mostly gravitate towards “you get errors earlier and thus can react before any production / customer / business data can be harmed”.
