go: proposal: Go 2: remove the "if" keyword and use "err?!" to avoid error handling boilerplate

This proposal looks ridiculous, but I think it has some good points, so I post it here anyway.

The proposal proposes that the if-block

if boolCondition {
   ...
} else {
  ...
}

should be simplified as

boolCondition? {
   ...
} else {
  ...
}

More generally, condition values can be of any type, instead of boolean types only:

condValue? {
   ...
} else {
   ...
}

which is equivalent to the current if-block as:

if condValue != zeroValueOfTypeOfCondValue {
   ...
} else {
  ...
}

In other words, the if keyword becomes useless and condValue is equvalent to condValue != zeroValueOfTypeOfCondValue. This really makes the proposal look ridiculous, but I think, currently in Go 1, the if-block and switch-case-block have too much functionality overlapping. In other words, I think the if keyword is not very essential for Go. This is one reason of removing the if keyword.

The other reason of removing the if keyword is we can use the following line

err? !

to simplify

err ? {
   return x, y, err
}

to avoid error handling boilerplate.

[update 1] To avoid breaking the current semicolon insertion rules, err? ! can be replaced with

err?;

err??

[update 2] Per Russ’s comment, condValue is equvalent to condValue != zeroValueOfTypeOfCondValue can be limited to boolean and error values only, or just excludes string values.

About this issue

Original URL
State: closed
Created 5 years ago
Reactions: 52
Comments: 22 (10 by maintainers)

Most upvoted comments

Excessive simplicity may be a burden.

+12

Aoang on Jul 12, 2019

If we replace the if keyword with the ? syntax, we’d also replace the else keyword with :.

cherrymui on Jul 12, 2019

We can’t realistically remove the if keyword at this point. It would break too many existing Go programs and too much existing Go documentation.

ianlancetaylor on Jul 11, 2019

I would already be happy with making either nil falsy everywhere oder just for the error type.

if err { return err}

This would already remove most of the error checking boilerplate and is very simple and straight forward. Go format can in addition force it to be in one line.

Even this would be simpler to write but not harder to read:

if err := Foo(); err { return err}

niondir on Aug 8, 2019

This is stupid.

vsg24 on Aug 2, 2019

In the upcoming 1.13 release we do have reflect.Value.IsZero (https://tip.golang.org/pkg/reflect/#Value.IsZero). Definitely more awkward to use than a builtin function.

ianlancetaylor on Jul 18, 2019

Note that if

x? {
    ...
}

is equivalent to

if x != zero-value-of-x {
    ...
}

then values of type error and values of type bool will behave somewhat differently. For a value of type error the block will be executed if there is an error. For values of type bool the block will be executed if the value is true. That is, with the typical meanings of those values, in one case we will execute the block if there is a problem, and in the other case we will execute the block if things are OK. This could be acceptable, but it’s worth considering.

ianlancetaylor on Jul 12, 2019

@rocket049 Thanks for the note. I encourage you to either explain your position, or just use the emojis on the first comment to express your opinion. Please see https://golang.org/wiki/NoPlusOne , although in this case I guess it’s really NoMinusOne. Thanks.

ianlancetaylor on Jul 12, 2019