Python

Imagine saying these operators out loud.

> is "is greater than"

So it makes sense to use >= as "is greater than or equal to"

You'd think = would be "is equal to", but it's already used for "set equal to" (i.e., assignment).

So what symbol do we use for "is equal to"? The symbol used in many programming languages is ==, so Python chose to follow that convention.

It's worth noting that there are other languages that use = as "is equal to", and use something else for assignment (like := for example). It just comes down to the history of the language and what conventions the original authors decided to use.

>= and <= match the mathematical operators. The question you want to ask is why doesn't it use = for equality, and the answer is that = is already used for assignment (inherited from C among other languages).

In theory a language could use = for assignment and equality but it might be a bit confusing and error prone. Maybe not though. Someone try it and report back.

It would be confusing and weird if "=" did different things depending on the context.

= is the assignment operator

== is the comparison operator.

the others using = only is probably just to keep things short, and the fact that the context is a lot clearer with another character like < next to the =

It’s all convention coming from older programming languages, particularly C, which comes from programmers wanting shorthand for things like “BRANCH_EQUAL $1 $2 $3” which is shorthand for some binary code.

Python has changed the logical and and or operators to be and and or instead of && and ||.

It's a convention set by early programming languages.

In most C-like languages, if (a = b)... is also a valid comparison. The = (assignment) operation returns the assigned value as a result, which is then converted to a boolean value by the if expression. Consider this Javascript code:

let a = b = 1

1. It first declares the b variable and assigns it the value of the expression 1, which is one.
2. It returns the result of the expression b = 1, which is the assigned value, which is 1.
3. It declares the a variable and assigns the previously returned value, which is 1.

Another example:

let a = 1
let b = 2
let c = 3
console.log(a == b) // prints "false" because the comparison is false
console.log(a = b) // prints 2 because the expression returns the value of the assignment, which is 'b', which is 2

// Using this in an 'if' statement:
if (b = c) { // the result of the assignment is 3, which is converted to a boolean true
    console.log("what")
}

You can't do the same in Python (it will fail with a syntax error), but it's better to adhere to convention because it doesn't hurt anyone, but going against it might confuse programmers who have greater experience with another language. Like I was when I switched from Pascal (which uses = for comparison and := for assignment) to C.

If I were to speculate, I'd say it came from the == operator (Boolean equality comparison) and then later, when that was extended to include Boolean less-than-or-equal and greater-than-or-equal, the decision was made to keep them 2 characters long. Either because it was visually cleaner, or just because programmers love being lazy (read: efficient)

It's still a mathematic operator. There's an entire field of math dedicated to comparisons, and it's featured heavily in most programming languages. Computer science is a field dedicated to the application of math

<= is already no mathematical assignment operator, but a comparison operator. Thus there is no need to define e.g. <== for comparing two values.

Pretty sure this is directly inspired by C so I would guess Guido van Rossum (the author of Python) just used what was already common back then. As in, = is assignment operator and == is equality/comparison operator.

https://en.cppreference.com/w/c/language/operator_comparison

I get your point of view, and haven't thought about it that way before.

As for why it's like that, my best guess is the sentence I wrote above. Your proposal totally makes sense.