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A comment on The ups and downs of porting 50k lines of C++ to Go (2015). Parent comment

Re:The ups and downs of porting 50k lines of C++ to Go (2015) by janekm on Thursday March 14, 2019 @05:56AM (#19387765)
Python supports slice[-1] for the last element... Pretty reasonable. Also slice[0:-1] etc. Swift also has a lot of array slice sugar, like array.last, array.endIndex, array.removeLast ... Obviously there is a trade-off to adding a lot of sugar to a language, in terms of learning the language, but leaving too little sugar in the language just leads to developers / library designers implementing the sugar themselves which leads to a whole mess of inconsistent code.
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Re:The ups and downs of porting 50k lines of C++ to Go (2015) by laumars on Thursday March 14, 2019 @06:06AM (#19387817)
> Python supports slice[-1] for the last element... Pretty reasonable.

Lots of languages offer something akin to that. If not `[-1]` then something more OO like `.last`. Even the language I wrote supports it. This is why I made the complaint about Go.

> Also slice[0:-1] etc.

In fairness, Go can do that. You just omit the value for where you want the last (or first) element of the slice or array. eg

  b := []byte("Hello, World")
  world := b[7:]
(this would work with strings too but I'm using a byte to make it clear we're working with slices)

edit: just for clarity I mean Go has the syntactic sugar for stating the start or end of a slice - rather than a negative number of elements from the end of the slice. My point being that there is already some syntactic sugar in specifying slices so it's a shame Go doesn't take that further.

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Re:The ups and downs of porting 50k lines of C++ to Go (2015) by 314 on Thursday March 14, 2019 @06:22AM (#19387900)
In python slice[0:-1] drops the last element. To get the same effect in Go you need world := b[:len(b)-1]. The len() needs to be there (your example is a different case).
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Re:The ups and downs of porting 50k lines of C++ to Go (2015) by laumars on Thursday March 14, 2019 @06:26AM (#19387926)
Yes, I was the one who made the comment about Go's lack of a -1 for slices in the first place. ;)

I was actually referencing the 0 part and thus saying Go does already have some syntactic sugar when dealing with slices. ie you can do:

   slice[5:]   // slice[:len(slice)]
but not

   slice[5:-1] // slice[:len(slice)-1]
Which is a great pity.

However I'll update my previous comment to make that clearer because I can totally understand how it reads confusingly.

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