81–90 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.
Traditionally? I don't think there was a "tradition". ":=" was used in Algol. "=" was used in Fortran. COBOL didn't use either "=" or ":=".
And most BASICs, though some (most?) required the keyword LET to introduce an assignment, as well.
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?
I don't understand the LISP line at all. I would have said "LET", "SET", and "EQUAL" (since it's talking about numbers). Is there something I'm missing? EDIT: It's since been changed to "let", "set", "equal" (but still lower-case).
I really wish more languages had an specific assignment operator.
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 ":=".
FORTRAN was far from the first high level language. Plankalkül for example was out a decade earlier and used →. EX: P1 max3 (V0[:8.0],V1[:8.0],V2[:8.0]) → R0[:8.0] https://en.wikipedia.org/wiki/Plankalk%C3%BCl So, there really was a lot of languages out there, but := was fairly common because it was easy to parse and type.
As far as := is concerned having to use the shift key for an assignment is less than ideal but there really aren't any better options on a modern keyboard. I think C's use of = is a bit braindamaged but it is nice and quick to type.
a := 5
You can also equivalently do
var a = 5
I almost never use the latter within functions (only at module scope).
I believe the former is forbidden except within functions.
It isn't just mathematically unsound, it's the cause of many errors, especially in C. Certainly a "million dollar mistake". A classic way to guard against accidental use of assignment in logic statements is to write it "backwards", i.e.: if (2 == x) {...} Since (2 = x) won't compile, while (x = 2) will not only compile but might appear to work for a very long time.
Earlier quoted context omitted.
Ditto. Fun fact: various dialects of BASIC let you optionally put LET before your assignment statements. So the following are equivalent: X = 10 LET X = 10
Wait...LET was optional? Auigh! Whole months of my childhood, wasted!
018 LET P=P K * B -
135 LET Q=1 F G / 1 - REC 0.00001 * - Q *
016 FOR X=1 STEP 1 UNTIL T
Because programming languages are typically designed for the tiny group of existing programmers than the much larger group of future programmers. The same reason unnecessary tokens exist, and 'drop' means delete in databases. It's entirely cultural.
Technically, DROP is used because DELETE is taken by something that deletes rows and using DELETE for tables and rows is a bit scary so you get DROP. I suspect quite a lot of naming happens that way.
Drop updates the logical structure without necessarily acting on the physical storage in a way commensurate with "deletion". You can this drop a million tuple table in a ms (less I expect) whilst deletion would take far, far longer (of the order of a million-times longer).
/guessing
Pascal got rid of the confusion.. := is assignment = is comparison. I really wish more languages had an specific assignment operator.
(Pascal is essentially the easy bits to implement from Algol68)