31–40 of 367 posts
Because K&R had terrible keyboards so they abbreviated everything as much as possible. Traditionally := was used for assignment, which makes sense since it is an asymmetric symbol for an asymmetric operation.
Another interesting way to think about it is as "match". That is try to match the stuff on the right with the stuff on the left. Take Erlang for example: 1> X = 1. 1 2> X = 2. ** exception error: no match of right hand side value 2 Notice variables are immutable (not just values themselves). Once X becomes 1, it can only match with 1 after that. You might think this is silly or annoying, why not just allow reassignme…
X = Y,
X = 5,
%% Y = 5 now as well
?- append([1,2], Y, [1,2,3]).
Y = [3].Is it really worth allowing assignment in places so weird that you also need ==? Wouldn't it be easier to use = for everything and get rid of those weird edge cases?
Because K&R had terrible keyboards so they abbreviated everything as much as possible. Traditionally := was used for assignment, which makes sense since it is an asymmetric symbol for an asymmetric operation.
That I believe is only Algol the more widely used 1st gen languages FORTRAN and COBOL used = As did PL1/G
Earlier quoted context omitted.
Traditionally? I don't think there was a "tradition". ":=" was used in Algol. "=" was used in Fortran. COBOL didn't use either "=" or ":=".
From the article: > Looking at this as a whole, = was never “the natural choice” the assignment operator. Pretty much everybody used := for assignment instead, possibly because = was so associated with equality. Nowadays most languages use = entirely because C uses it, and we can trace C using it to CPL being such a clusterfuck.
Another interesting way to think about it is as "match". That is try to match the stuff on the right with the stuff on the left. Take Erlang for example: 1> X = 1. 1 2> X = 2. ** exception error: no match of right hand side value 2 Notice variables are immutable (not just values themselves). Once X becomes 1, it can only match with 1 after that. You might think this is silly or annoying, why not just allow reassignme…
Since the equal sign is an assertion of truth, and since assertions cause a crash on failure, you can pretty much derive the rest of the language/BEAM characteristics from that.
When it reads as "let x equal y" it makes sense. I think it makes good sense for imperative programming. It makes slightly less sense for functional programming. For declarative configuration, I think a colon makes much more sense.
About once every year I have a brain fart on a sleepy morning and confuse myself by using = for comparitors and or == for assignment... shortly followed by "Nnarhh". [edit] :P LOL at downvotes, HN is no place for silly annecdotes "this is serious things we dooo".
more broadly, why schools are merging reduction and equality in arithmetic ?
Because K&R had terrible keyboards so they abbreviated everything as much as possible. Traditionally := was used for assignment, which makes sense since it is an asymmetric symbol for an asymmetric operation.
There’s also <-, most commonly seen in R but draws it’s heritage from the APL keyboard