为什么在Go中为变量赋等号

Question

I would like to say upfront that I'm only starting to learn about and use the Go language and also that this isn't a syntax question but more of a language design question.

In Go, assuming that you have a channel c of int, you can send on the channel using:

c <- 1

And receive from the channel into a variable v with:

v = <- c

I've read that a simple way to remember the syntax is that the "arrow" points in the direction in which information is flowing, which I think is poetic, especially being quite the Python fan. My question is why is this not taken all the way so you have the symmetric syntax:

v <- c

in order to receive from a channel? Why have the equals sign there?

I suppose the interpreter would end up with adjacent syntax tokens like:

[variable][value]

which could conceivably come from a statement like:

v 1 

So that the equals sign there allows you to reuse the usual variable assignment machinery by making that channel receipt evaluate to a value. Would it be that difficult to make the interpreter accept the version without the equals sign though? It would basically just have to treat it as a binary operator for that case.

It also seems to lead to other cases where if there are two channels c1 and c2 you have the syntax:

c2 <- <- c1

In order to read from one and transmit it into the other.

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I'd like to also say that I'm not trying to elicit opinions on style but rather trying to understand the decisions drove Go to be the way it is.

Answer 1

Combining two orthogonal operators each doing one thing is much more expressive.

In addition to the examples provided by @sedat-kapanoglu, think how would you express the following:

x := <-ch
x += <-ch
x, y = <-ch1, <-ch2

Also with your proposal the following expression:

y <- x

could be a read from a channel x or a write to a channel y depending on the types x and y. Compare it to the code that uses the existing syntax:

y = <-x
y <- x