[Issue 4591] Concat of std.typecons.Tuples

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=4591

--- Comment #4 from github-bugzi...@puremagic.com ---
Commit pushed to master at https://github.com/dlang/phobos

https://github.com/dlang/phobos/commit/cddd0df51a50e2c370162daa7ed7fca0dad4b979
Fix Issue 4591, 14637 - Array operations should work on tuples

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[Issue 4591] Concat of std.typecons.Tuples

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=4591

github-bugzi...@puremagic.com changed:

   What|Removed |Added

 Status|ASSIGNED|RESOLVED
 Resolution|--- |FIXED

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[Issue 4591] Concat of std.typecons.Tuples

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=4591

Seb  changed:

   What|Removed |Added

   Keywords||pull
 CC||greensunn...@gmail.com

--- Comment #3 from Seb  ---
https://github.com/dlang/phobos/pull/6386

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[Issue 4591] Concat of std.typecons.Tuples

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=4591

Andrei Alexandrescu  changed:

   What|Removed |Added

   Keywords||bootcamp

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[Issue 4591] Concat of std.typecons.Tuples

[d-bugmail]

http://d.puremagic.com/issues/show_bug.cgi?id=4591


bearophile_h...@eml.cc changed:

   What|Removed |Added

 AssignedTo|and...@erdani.com   |nob...@puremagic.com


--- Comment #2 from bearophile_h...@eml.cc 2013-05-14 09:49:37 PDT ---
I suggest to add the support for Tuple concatenation and join:

In Python 2.6:

 t1 = (1, 2)
 t1 + t1
(1, 2, 1, 2)
 t1 + (3,)
(1, 2, 3)


Proposed D syntax:

void main() {
import std.typecons;
auto t1 = tuple(1, 2);
auto t2 = t1 ~ t1;
auto t3a = t1 ~ 3;
auto t3b = t1 ~ tuple(3);
}


An use case, this computes the frequency of the first digit (Benford's Law):


import std.stdio, std.range, std.math, std.conv, std.bigint,
   std.algorithm;

auto benford(R)(R data) {
auto heads = data.filter!q{a != 0}.map!q{ a.text[0] - '1' }.array;
immutable double k = heads.length;
return iota(1, 10)
   .zip(heads.sort().group.map!(p = p[1] / k))
   .map!q{ [a[]] ~ log10(1.0 + 1.0 / a[0]) };
}

void main() {
auto fibs = recurrence!q{a[n - 1] + a[n - 2]}(1.BigInt, 1.BigInt);

writefln(%9s %9s %9s, Actual, Expected, Deviation);
foreach (p; fibs.take(1000).benford)
writefln(%1.0f: %5.2f%% | %5.2f%% | %5.4f%%,
 p[0], p[1] * 100, p[2] * 100, abs(p[2] - p[1]) * 100);
}


Currently the benford() function returns a range of double[]:

.map!q{ [a[]] ~ log10(1.0 + 1.0 / a[0]) };

If I want to return a range of 3-tuples:

.map!q{ tuple(a[], log10(1.0 + 1.0 / a[0])) };

With the proposed syntax the code becomes:

.map!q{ a ~ log10(1.0 + 1.0 / a[0]) };

Or:

.map!q{ a ~ tuple(log10(1.0 + 1.0 / a[0])) };

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[Issue 4591] Concat of std.typecons.Tuples

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--- Comment #1 from bearophile_h...@eml.cc 2011-07-25 05:30:07 PDT ---
Slicing too is sometimes useful:

import std.typecons;
void main() {
auto t1 = tuple(10, 20, 30, 40, 50);
auto t2 = tuple(100, 200, 300);
auto t3 = t1[0 .. 2]; // tuple slicing
auto t4 = t1 ~ t2;// tuple concat
}

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[Issue 4591] Concat of std.typecons.Tuples

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Andrei Alexandrescu and...@metalanguage.com changed:

   What|Removed |Added

 Status|NEW |ASSIGNED
 CC||and...@metalanguage.com
 AssignedTo|nob...@puremagic.com|and...@metalanguage.com


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