Hi, I have been wondering if there is a reason for not making for not making the initialization of variables explicit. I think this is done very elegantly in golang with the “:=” operator. Like this one would know exactly when an entirely new variable shall be introduced (and one could also think a…

I was not aware of that, maybe you are right. However I do not know if this is feasible if you just want to create a single variable since it blows up code size. Also it adds another layer of nesting which may be undesirable. However, maybe it would make sense to define for i=1:10 x:=i+1 ... …

[image] peteole: eason for not including this feature in julia historically or if it was just that it was not thought about and if the rea We already have scope keyword, like global and local. := is not needed. Scope keywords are more flexible than := because they can also be used on functio…

[image] peteole: So what did I miss in my considerations? AFAIK this was an explicit design choice: having different syntax for introducing variables into a scope and assignment is something that programmers used to Python, R, Matlab, etc, may find inconvenient. This came up in the (epic) sc…

I actually don’t think that would be such an unreasonable proposal. I am assuming there could then only ever be one := per variable name in each scope and multiple ones would be a syntax error? The main question here is just whether this pattern is used often enough to warrant its own syntax. I thin…

I would love to have a := 3 as a shorthand for a::Int = 3 (and have it work in global scope)! So I think := could serve two purposes that often go together: Make sure a variable is not re-declared by mistake. Give the variable a fixed type inferred by the value on the right-hand side. This means …

AFAIK not requiring explicit declarations for locals was an explicit design choice for Julia. Cf eg [image] Why not an even-harder scope? Internals & Design Having a lot of time thinking about it, I really believe that our current design is very close to optimal given jus…

Having recently learned Go (where := is used very much), I was very pleased with the middle ground that they have in that kind of code between explicit scope and syntactic parsimony. My own background is heavily influenced by an older tradition of Scheme (and Julia is very much of a Schemish flavor…

That makes my head hurt. :slight_smile:

Perl had a similar feature where you would have to write my $var = 0; upon the first use. It’s like int var = 0 in C but without the type. The advantages are code readability (a visible guarantee that this is the first use) and catching of typos. If you typo’d $car = 1 later on, it’d be a synta…

This is certainly an interesting design direction that’s fun to think through. You would want something like this: := is required to initialize a variable, = can only be used to update an existing variable. That would take some getting used to for people coming from Python, R or Matlab, who are unac…

Why no := operator for initializing variables

Internals & Design

Tamas_Papp June 15, 2021, 3:49pm 11

AFAIK not requiring explicit declarations for locals was an explicit design choice for Julia. Cf eg

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Why no := operator for initializing variables

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