Mindblowing features are basically, by definition, a result of bad language design. They blow your mind, since they are totally unexpected behaviours. They may still be cool, but they are unexpected and hence unintuitive.
A language that are full of these is Perl. And one simple one is that you can take the string “AAAAA” and use addition on that, like “AAAAA”++ and you will get the result “AAAAB”. Cool you may think, but is it really? Addition is normally used to increase the value of a number, that is a completely different operation than modifying a String. The string “AAAAA” cannot be said to be greater or less than “AAAAB”, besides the very special case when we order it. But in general the name “John” is not considered to be higher/lower than “Mark”, they are just different. So, even if it is cool to manipulate strings by using addition/subtraction, it is still bad language design and very unintuitive. Also, since perl is so loosely typed, it may also cause very unexpected bugs.
strcmp() returns an integer indicating the result of the comparison, as follows:
0, if the s1 and s2 are equal;
a negative value if s1 is less than s2;
a positive value if s1 is greater than s2.
So basically, if C had higher level constructs, it would be identical to Rust here.
So, even if it is cool to manipulate strings by using addition/subtraction, it is still bad language design and very unintuitive.
Rust has implAdd<&str> forString and implAddAssign<&str> forString. Both append as expected.
But maybe you meant numeric addition specifically.
In that case, yes, Rust doesn’t have that, although it’s an impl<'a> Step for &'astr away from having something similar (it would be ("AAAAA"..).next()).
implStepforchar already exists of course, but shouldn’t if we take your argument to its logical conclusion.
Oh, and C would most definitely have this feature if it could. Numerical manipulation of chars is commonplace there.
Rust has impl Add<&str> for String and impl AddAssign<&str> for String. Both append as expected.
I wouldn’t go so far and say “as expected”: “Addition” implies that we’re dealing with a ring, that there’s also multiplication, and that really doesn’t make sense for strings (unless you indeed consider them numbers). It’s why Haskell’s Monoid typeclass comes with the function mappend, not madd.
In Rust’s defence though std::ops traits aren’t meant to carry any semantics they’re about syntax: It’s called Add because it’s +, not because it means something. I do think it would’ve been worth it to introduce ++ for general appending (also vectors, sets, maps, etc), though, to keep things clean. Also ++= for the mutating case.
I do think it would’ve been worth it to introduce ++ for general appending.
I already mentioned (val..).next() which is both safe* and explicit about it being a generic stepping operation instead of possibly being sugar for {x = x + 1; x}.
Also, calling it “appending” is weird for us folks coming from languages like C 😉
* you don’t have to worry about what i32::MAX++ would/should return.
Mindblowing features are basically, by definition, a result of bad language design. They blow your mind, since they are totally unexpected behaviours. They may still be cool, but they are unexpected and hence unintuitive.
A language that are full of these is Perl. And one simple one is that you can take the string “AAAAA” and use addition on that, like “AAAAA”++ and you will get the result “AAAAB”. Cool you may think, but is it really? Addition is normally used to increase the value of a number, that is a completely different operation than modifying a String. The string “AAAAA” cannot be said to be greater or less than “AAAAB”, besides the very special case when we order it. But in general the name “John” is not considered to be higher/lower than “Mark”, they are just different. So, even if it is cool to manipulate strings by using addition/subtraction, it is still bad language design and very unintuitive. Also, since perl is so loosely typed, it may also cause very unexpected bugs.
The general theme of your comment is good, but the example is…
// rust eprintln!("{}", "AAAAB" > "AAAAA") // true eprintln!("{}", "Mark" > "John") // true// C printf("%d\n", strcmp("AAAAB", "AAAAA")); // 1 printf("%d\n", strcmp("Mark", "John")); // 1strcmp()docs:So basically, if C had higher level constructs, it would be identical to Rust here.
Rust has
impl Add<&str> for Stringandimpl AddAssign<&str> for String. Both append as expected.But maybe you meant numeric addition specifically.
In that case, yes, Rust doesn’t have that, although it’s an
impl<'a> Step for &'a straway from having something similar (it would be("AAAAA"..).next()).impl Step for charalready exists of course, but shouldn’t if we take your argument to its logical conclusion.Oh, and C would most definitely have this feature if it could. Numerical manipulation of
chars is commonplace there.I wouldn’t go so far and say “as expected”: “Addition” implies that we’re dealing with a ring, that there’s also multiplication, and that really doesn’t make sense for strings (unless you indeed consider them numbers). It’s why Haskell’s
Monoidtypeclass comes with the functionmappend, notmadd.In Rust’s defence though
std::opstraits aren’t meant to carry any semantics they’re about syntax: It’s calledAddbecause it’s+, not because it means something. I do think it would’ve been worth it to introduce++for general appending (also vectors, sets, maps, etc), though, to keep things clean. Also++=for the mutating case.I already mentioned
(val..).next()which is both safe* and explicit about it being a generic stepping operation instead of possibly being sugar for{x = x + 1; x}.Also, calling it “appending” is weird for us folks coming from languages like C 😉
* you don’t have to worry about what
i32::MAX++would/should return.I hate it to break it to you but it’s the same with numbers.
Ok, I then have some business proposals…