I understand Rust being type safe, but Im seeing syntax that Ive never seen in my life in Go which looks too messy

var test int < bruh what?

:=

func(u User) hi () { … } Where is the return type and why calling this fct doesnt require passing the u parameter but rather u.hi().

map := map[string] int {} < wtf

  • BatmanAoD
    3·
    7 months ago

    I was curious about the Python connection because multiple comments mentioned it, but I’ve worked on multiple Python projects over the past dozen-ish years and never seen that operator.

    Turns out it was introduced in 3.8, released in 2019, so it was much too late to inspire Go, and most of the projects I’ve worked on were written to target an earlier Python version. It also has a substantially different meaning than in Go.

    I don’t know if there’s an “official” rationale for the Go syntax, but := is a fairly common (but not ubiquitous) math notation meaning “define the thing on the left to be equal to the expression on the right”, i.e. to distinguish it from the other use of =, i.e. “the expression on the left must be equal to the expression on the right.” Go’s usage matches this mathematical meaning of introducing a new variable definition pretty well.

    • thingsiplay@beehaw.org
      1·
      7 months ago

      Turns out it was introduced in 3.8, released in 2019, so it was much too late to inspire Go

      You are probably right about that. But don’t forget that the operator didn’t made it day one, there was lot of discussion before and probably testing it in the beta releases before. But given how old Golang at that point is, you are right about my take on inspiration. This operator wasn’t a new invention in Python.

      It also has a substantially different meaning than in Go.

      I don’t know if there’s an “official” rationale for the Go syntax, but := is a fairly common (but not ubiquitous) math notation meaning “define the thing on the left to be equal to the expression on the right”, i.e. to distinguish it from the other use of =, i.e. “the expression on the left must be equal to the expression on the right.”

      Does it though? In both cases, Go and Python, the operator will assign a variable a value and also use it as an expression. That is useful in cases like for loops or other cases where you want immediately use the variable content as an expression. This cannot be done with the regular assignment operator a = 69, which itself is not an expression. So in practical terms, its the same in usability for Go and Python. So its doing the same for both languages and has the same differences to the assignment operator. (Edit: Read the reply, I learned something myself. That’s why its important that you don’t blindly teach people like I did.)

      • BatmanAoD
        3·
        7 months ago

        In both cases, Go and Python, the operator will assign a variable a value and also use it as an expression.

        That is absolutely not true. foo := <expr> is a statement in Go, full stop. Just try something trivial like assigning to the output of :=: https://go.dev/play/p/nPINGc7LO8B

        It’s true that if and for let you use := but don’t let you use var, but you still can’t use the result of the assignment directly. So for instance you need if foo := <expr>; foo { ... } rather than just if foo := <expr> { ... }.

        • thingsiplay@beehaw.org
          3·
          7 months ago

          Ok I see, I stand corrected then. Its a misconception I had without actually going through all of this, so my bad (will edit my replies to mark them). At least in Python we can do this print(foo := (bar := 3)) but not on its own as foo := 3 .