> 1 + "1"
(irb):1:in 'Integer#+': String can't be coerced into Integer (TypeError)
from (irb):1:in '<main>'
from <internal:kernel>:168:in 'Kernel#loop'
from /Users/george/.rvm/rubies/ruby-3.4.2/lib/ruby/gems/3.4.0/gems/irb-1.14.3/exe/irb:9:in '<top (required)>'
from /Users/george/.rvm/rubies/ruby-3.4.2/bin/irb:25:in 'Kernel#load'
from /Users/george/.rvm/rubies/ruby-3.4.2/bin/irb:25:in '<main>'
Some people mistakenly call dynamic typing "weak typing" because they don't know what those words mean. PSA:
Static typing / dynamic typing refers to whether types are checked at compile time or runtime. "Static" = compile time (eg C, C++, Rust). "Dynamic" = runtime (eg Javascript, Ruby, Excel)
Strong / weak typing refers to how "wibbly wobbly" the type system is. x86 assembly language is "weakly typed" because registers don't have types. You can do (more or less) any operation with the value in any register. Like, you can treat a register value as a float in one instruction and then as a pointer during the next instruction.
Ruby is strongly typed because all values in the system have types. Types affects what you can do. If you treat a number like its an array in ruby, you get an error. (But the error happens at runtime because ruby is dynamically typed - thus typechecking only happens at runtime!).
It's strongly typed, but it's also duck typed. Also, in ruby everything is an object, even the class itself, so type checking there is weird.
Sure it stops you from running into "'1' + 2" issues, but won't stop you from yeeting VeryRawUnvalidatedResponseThatMightNotBeAuthorized to a function that takes TotalValidatedRequestCanUseDownstream. You won't even notice an issue until:
- you manually validate
- you call a method that is unavailable on the wrong object.
I recall a type theorist once defined the terms as follows (can't find the source): "A strongly typed language is one whose type system the speaker likes. A weakly typed language is one whose type system the speaker dislikes."
So yeah I think we should just give up these terms as a bad job. If people mean "static" or "dynamic" then they can say that, those terms have basically agreed-upon meanings, and if they mean things like "the type system prohibits [specific runtime behavior]" or "the type system allows [specific kind of coercion]" then it's best to say those things explicitly with the details filled in.
It would be weak if that was actually mutating the first “a”. That second declaration creates a new variable using the existing name “a”. Rust lets you do the same[1].
Rust lets you do the same because the static typing keeps you safe. In Rust, treating the second 'a' like a number would be an error. In ruby, it would crash.
These are two entirely different a's you're storing reference to it in the same variable. You can do the same in rust (we agree it statically and strongly typed, right?):
let a = 1;
let a = '1';
Strongly typing means I can do 1 + '1' variable names and types has nothing to do with it being strongly typed.
In the dynamic world being able to redefine variables is a feature not a bug (unfortunately JS has broken this), even if they are strongly typed. The point of strong typing is that the language doesn't do implicit conversions and other shenanigans.
Well yeah, because variables in what you consider to be a
strongly typed language are allocating the storage for those variables. When you say int x you're asking the compiler to give you an
int shaped box. When you say x = 1 in Ruby all you're doing is saying is that in this scope the name x now refers to the box holding a 1. You can't actually store a string in the int box, you can only say that
from now on the name x refers to the string box.
