In the last days of beta3 D+Phobos is getting better in small but significant ways:

immutable s = ["red", "blue"];
auto js = s.join;

This is very handy because you can join arrays from constant function arguments, or the result of a map that yields const items, etc.

-----------------------

And I am finding the optional column number in error messages very handy, my editor/IDE often jumps at the right column, saving me tiny amounts of time that adds up making the debugging nicer. The experience is just better than before.

-----------------------

auto r = [10, 20, 30].sum;

This has replaced me tens of usages of:
alias sum = reduce!q{a + b};
Or:
alias sum = curry!(reduce!q{a + b}, 0);


But I have found problems because currently sum(int[]) returns a long, see the discussion so far:
https://d.puremagic.com/issues/show_bug.cgi?id=12169

Bye,
bearophile

On Sunday, 16 February 2014 at 13:22:09 UTC, bearophile wrote:
> In the last days of beta3 D+Phobos is getting better in small but significant ways:
>
> immutable s = ["red", "blue"];
> auto js = s.join;
>
> This is very handy because you can join arrays from constant function arguments, or the result of a map that yields const items, etc.
>
> -----------------------
>
> And I am finding the optional column number in error messages very handy, my editor/IDE often jumps at the right column, saving me tiny amounts of time that adds up making the debugging nicer. The experience is just better than before.
>
> -----------------------
>
> auto r = [10, 20, 30].sum;

There is the nice old Smalltalk-80 inject:into: method in the Collection class:

| list sum |
list := OrderedCollection new add: 1; add: 2; add: 3; yourself.
sum := list inject: 0 into: [ :a :b | a + b ].
Transcript cr; show: sum.  "prints 6"

A little more general ;-). The Scala guys have also cloned it where it is called foldLeft.

Bienlein:

> There is the nice old Smalltalk-80 inject:into: method in the Collection class:
>
> | list sum |
> list := OrderedCollection new add: 1; add: 2; add: 3; yourself.
> sum := list inject: 0 into: [ :a :b | a + b ].
> Transcript cr; show: sum.  "prints 6"
>
> A little more general ;-). The Scala guys have also cloned it where it is called foldLeft.

In D there's std.algorithm.reduce.
I think Scala guys have copied something older than Smalltalk.

Bye,
bearophile

On Wed, Feb 19, 2014 at 1:29 PM, Bienlein <jeti789@web.de> wrote:
> There is the nice old Smalltalk-80 inject:into: method in the Collection class:

> A little more general ;-). The Scala guys have also cloned it where it is called foldLeft.

Oh, but D has `reduce`, for years now. It was maybe one of the very first range algorithms to be put into Phobos, with map and filter. So we have generality already :-)

What bearophile wanted was, on the contrary, to have a specialized-for-summing function, if only to make the intended behavior more clear.

Hm, I got next error on this code

import std.stdio;
import std.array;

void main()
{
immutable s = ["red", "blue"];
auto js = s.join;
}


D:\Project\2014\App1\main.d(7): Error: template std.array.join cannot deduce function from argument types !()(immutable(char[][])), candidates are:
C:\D\dmd2\windows\bin\..\..\src\phobos\std\array.d(1526):        std.array.join(RoR, R)(RoR ror, R sep) if (isInputRange!RoR && isInputRange!(ElementType!RoR) && isInputRange!R && is(Unqual!(ElementType!(ElementType!RoR)) == Unqual!(ElementType!R)))
C:\D\dmd2\windows\bin\..\..\src\phobos\std\array.d(1573):        std.array.join(RoR)(RoR ror) if (isInputRange!RoR && isInputRange!(ElementType!RoR))
[Finished in 0.3s]

On Wednesday, 19 February 2014 at 12:43:10 UTC, Philippe Sigaud wrote:
>
> What bearophile wanted was, on the contrary, to have a
> specialized-for-summing function, if only to make the intended
> behavior more clear.

I see. Unhappily, I don't have a D compiler handy. Would this compile:

immutable s = ["red", "blue"].sum

If not, it would be interesting to understand how that works :-)

-- Bienlein

On Wednesday, 19 February 2014 at 13:07:39 UTC, Suliman wrote:
> Hm, I got next error on this code
>
> import std.stdio;
> import std.array;
>
> void main()
> {
> immutable s = ["red", "blue"];
> auto js = s.join;
> }

This works:

auto s = ["red", "blue"];
auto js = s.join("");

2 issues in your snippet:

1) need to define separator for join
2) fully immutable array can't act is InputRange as one can't popFront from it

Arguably join should have made constraint check on tail-qualified copy of s instead though (as it is legal to copy imutable(char[]) into immutable(char)[]). I bet there is even bugzilla entry for it :)

On Wednesday, 19 February 2014 at 13:18:15 UTC, Bienlein wrote:
> I see. Unhappily, I don't have a D compiler handy. Would this compile:
>
> immutable s = ["red", "blue"].sum
>
> If not, it would be interesting to understand how that works :-)
>
> -- Bienlein

This works right now: immutable s = ["red", "blue"].join("");

On 02/19/2014 02:21 PM, Dicebot wrote:
>
>
> 2 issues in your snippet:
>
> 1) need to define separator for join

No, a custom separator is not mandatory.

On Wed, Feb 19, 2014 at 2:18 PM, Bienlein <jeti789@web.de> wrote:
> I see. Unhappily, I don't have a D compiler handy. Would this compile:
>
> immutable s = ["red", "blue"].sum
>
> If not, it would be interesting to understand how that works :-)

It won't work, since binary + is not defined for strings. I don't understand what you want, here.