Equals: a sign or assign

I enjoyed reading “How I learned to stop worrying and love the code” and as a teacher of The Code I took it to heart.

Number 3 is huge, I think. Most people think they know what this means

hello = 4

so if we don’t tell them straight away that it means something else, they might be confused for some time. I guess we can blame Fortran for originally abusing the “equals sign” that way, but that doesn’t really excuse all the languages that have repeated the blunder since then.

I think part of the issue is verbal. When I learned Pascal, which has a distinct assignment operator,

hello := 4

I developed the habit of pronouncing it “hello gets four” and that continues to this day… even in languages that use an equals sign. I’ve noticed that lots of programmers pronounce

hello = 4

“hello equals four,” even though they also pronounce

hello == 4

“hello equals four.” Having a verbal distinction between “hello gets four” and “hello equals four” is useful, in my mind. In practice, though, it’s not that helpful since few people I end up in a code review or pair programming situation with do the same.

It’s also worth noting that

hello = 4

means something a little different in Python, than in most other languages. Namely, it’s binding a name rather than assigning a value. This means that in addition to tripping up beginning programmers, it also trips up experienced programmers who are new to Python.

It means another thing in Erlang and yet another in Elixir. Both of these are matching, rather than simply assigning, but in slightly different ways. Again, this trips up experienced programmers who are new to Erlang or Elixir. It doesn’t mean “equals,” so the beginning programmers are confused, but it doesn’t mean “simple assignment” either, so the experienced programmers are confused too. It doesn’t even mean “bind,” so the Python programmers are confused as well.

I have often wondered if teaching Elixir to beginning programmers might be easier than teaching it to experienced programmers. Teaching Elixir (or Erlang or Clojure or any functional language) to someone who already knows imperative programming seems to involve as much un-learning as learning. If someone didn’t have any baggage from imperative programming, we could just teach them functional programming straight away. Someday, I’d like to try this.

Equals: a sign or assign

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