3 ms·

Here's one reason why sigils could be considered to suck. `@array` - array of values. `$array[1]` - get element 1 of the array. `$array` - What do you think

Here's one reason why sigils could be considered to suck. `@array` - array of values. `$array[1]` - get element 1 of the array. `$array` - What do you think this does? Why can't we just `@array[1]`?

hedora 4y ago
The last one produces a helpful error message at script interpretation time. @array[1] is probably also an error, or you're doing something very strange / wrong, and it'll stick out like a sore thumb during code reviews.
csdvrx 4y ago
> `$array` - What do you think this does? I think it will throw an error if you declared my @array > Why can't we just `@array[1]`? Because that could return an array or a hash if you are dealing with structures likes arrays-of-arrays (AoA) or arrays-of-hashes (AoH). To my naive take, it makes much more sense to only identify high level objects to put them under one category (arrays, AoA, AoH -> @) then consider everything else as "uncertain" and default to $. Otherwise, you would have to declare AoA and AoH differently (ex: my @@AoA; my @%AoH;) and then the interpreter could see @AoA[1] and %AoH[1] as valid but %AoA[1] and @AoH[1] as invalid. I could see that as potentially having value to know at a glance what you are dealing with, but it might break many things, and casting to a new object with my %aoh_1 = %{ $AoH[1] } makes more sense.
- deleted 4y ago
  [deleted]
- jwilk 4y ago
  > Because that could return an array or a hash @array[1] returns a single-element list-like thing. It mostly works, but you get a warning: https://perldoc.perl.org/perldiag#Scalar-value-@%25s%5B%25s%5D-better-written-as-$%25s%5B%25s%5D https://perldoc.perl.org/perldiag#Scalar-value-@%25s%5B%25s%...
G3rn0ti 4y ago
Raku actually adopted that latter syntax. Although, it’s optional as everything really becomes a reference anyway. So you don’t need the „@“ and „%“ sigils any more.
xorcist 4y ago
Perl has "contexts" as its type system. Sigils are a part of that. There's a lesson here somewhere that most people don't generally want to understand stuff. So stuff that's the least bit different don't tend to go mainstream, things like Haskell have a hard time. Perl was a bit different but just happened to go mainstream anyway, and that probably coloured people's feelings for it, for better and for worse.
bmn__ 4y ago
> Why can't we just `@array[1]`? Because of slices. If you look at the complete table, you will never get confused again. https://news.ycombinator.com/item?id=26578855 https://news.ycombinator.com/item?id=26578855
gnubison 4y ago
Sigils indicate what an operation evaluates to, not what the input type is. You get used to it.
matthewpersico 4y ago
Because Perl is context sensitive and what we care about is not what is being stored but what is being accessed. 'array' is the variable. '@array' gives me the list in 'array'. '$array[1]' gives me the scalar ($) value at array[1]. `@array[3..7]` gives me the list (@) of values at array indexes 3-7, inclusive on both sides. (Why does Python use open ended ranges? <facepalm>) (Why is Python's slicing syntax an inflexible loop? <facepalm again>) `@array[1]`, by the way gives me the list of values at array index 1, which is the same as `$array[1]`

Here's one reason why sigils could be considered to suck. `@array` - array of values. `$array[1]` - get element 1 of the array. `$array` - What do you think this does? Why can't we just `@array[1]`?

hedora 4y ago

The last one produces a helpful error message at script interpretation time. @array[1] is probably also an error, or you're doing something very strange / wrong, and it'll stick out like a sore thumb during code reviews.

csdvrx 4y ago

> `$array` - What do you think this does? I think it will throw an error if you declared my @array > Why can't we just `@array[1]`? Because that could return an array or a hash if you are dealing with structures likes arrays-of-arrays (AoA) or arrays-of-hashes (AoH). To my naive take, it makes much more sense to only identify high level objects to put them under one category (arrays, AoA, AoH -> @) then consider everything else as "uncertain" and default to $. Otherwise, you would have to declare AoA and AoH differently (ex: my @@AoA; my @%AoH;) and then the interpreter could see @AoA[1] and %AoH[1] as valid but %AoA[1] and @AoH[1] as invalid. I could see that as potentially having value to know at a glance what you are dealing with, but it might break many things, and casting to a new object with my %aoh_1 = %{ $AoH[1] } makes more sense.

deleted 4y ago
[deleted]
jwilk 4y ago
> Because that could return an array or a hash @array[1] returns a single-element list-like thing. It mostly works, but you get a warning: https://perldoc.perl.org/perldiag#Scalar-value-@%25s%5B%25s%5D-better-written-as-$%25s%5B%25s%5D https://perldoc.perl.org/perldiag#Scalar-value-@%25s%5B%25s%...

G3rn0ti 4y ago

Raku actually adopted that latter syntax. Although, it’s optional as everything really becomes a reference anyway. So you don’t need the „@“ and „%“ sigils any more.

xorcist 4y ago

Perl has "contexts" as its type system. Sigils are a part of that. There's a lesson here somewhere that most people don't generally want to understand stuff. So stuff that's the least bit different don't tend to go mainstream, things like Haskell have a hard time. Perl was a bit different but just happened to go mainstream anyway, and that probably coloured people's feelings for it, for better and for worse.

bmn__ 4y ago

> Why can't we just `@array[1]`? Because of slices. If you look at the complete table, you will never get confused again. https://news.ycombinator.com/item?id=26578855 https://news.ycombinator.com/item?id=26578855

gnubison 4y ago

Sigils indicate what an operation evaluates to, not what the input type is. You get used to it.

matthewpersico 4y ago

Because Perl is context sensitive and what we care about is not what is being stored but what is being accessed. 'array' is the variable. '@array' gives me the list in 'array'. '$array[1]' gives me the scalar ($) value at array[1]. `@array[3..7]` gives me the list (@) of values at array indexes 3-7, inclusive on both sides. (Why does Python use open ended ranges? <facepalm>) (Why is Python's slicing syntax an inflexible loop? <facepalm again>) `@array[1]`, by the way gives me the list of values at array index 1, which is the same as `$array[1]`