Why there is no int64Slice on sort when we have a float64Slice

[Sankar]

I have an array of int64s which are generated by storing time differences in nano seconds.

times := make([]int64, n)

for i:=0; i < n; i++ {

        t0 := time.Now()

        //some operation

        t1 := time.Now()

times[i] = (t1.Sub(t0)).Nanoseconds()

}

Now I want to sort this times array but I cannot find a suitable Int64Slice datatype. The sort.Ints function too work only with int datatype and not int64. Why is this so ? 

[si guy]

Just a guess, but it may have something to do with the forthcoming int being 64 bits wide on amd64. Or it's missing because no one needed it.

[Kyle Lemons]

Because it's four lines of code:

type int64arr []int64

func (a int64arr) Len() int { return len(a) }

func (a int64arr) Swap(i, j int} { a[i], a[j] = a[j], a[i] }

func (a int64arr) Less(i, j int) bool { return a[i] < a[j] }

Float64 is the more common float, int is the more common it, so both have predefined versions of this.

[Sankar P]

Hm. Ok. But for my taste, it kind of feels odd to not have an API for default bit but 64-bit alone (in case of float) and default-bit-size alone but not for 64 bit. I would not have been surprised had there been no IntSlice type existed at all.

--
Sankar P
http://psankar.blogspot.com

[Russ Cox]

> Hm. Ok. But for my taste, it kind of feels odd to not have an API for
> default bit but 64-bit alone (in case of float) and default-bit-size alone
> but not for 64 bit. I would not have been surprised had there been no
> IntSlice type existed at all.

The slices exist for the default types taken by constants: 1 (int), ""
(string), and 1.0 (float64). We stopped there.

Russ

[Jan Mercl]

On Mon, Sep 24, 2012 at 5:37 PM, Sankar <sankar.c...@gmail.com> wrote:
> Now I want to sort this times array but I cannot find a suitable Int64Slice
> datatype.

Here you (may) go: http://go.pkgdoc.org/github.com/cznic/sortutil

-j

[Sankar P]

Thanks.

But I went ahead with my own four lines already similar to what Kyle Lemmons wrote :) I was curios about the reasoning behind the decision.

[Sankar P]

ah okay.

But in a 32 bit machine, f := 1.0 will take it as float64 or float ? 

I should have checked it myself but sorry I do not have access to a 32 bit machine at the moment. 

Thanks.

[Patrick Mylund Nielsen]

There is no float; just float32 and float64. Float64 is the more common.

--
 
 

[Sankar P]

I accept that float64 is the most common and I dont debate that float32Slice should have been there by default (thought I didnt understand why it didnt exist until I sent the mail here).

I was just curios to know if on a 32 bit machine, f := 1.0 will create a float64 type or float32 type. 

Thanks

[Patrick Mylund Nielsen]

Ah, I thought you meant float64 vs. float (which doesn't exist.)

In any case, the default type for the constant 1.0 is float64: http://golang.org/ref/spec#Constant_expressions