Re: [OT] Re: merkle reverse
On Thursday, 5 April 2018 at 14:58:21 UTC, Andy Smith wrote: On Thursday, 5 April 2018 at 08:12:38 UTC, aerto wrote: This is the bitcoin genesis block merkle root 4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b how i can get it at this format 3ba3edfd7a7b12b27ac72c3e67768f617fc81bc3888a51323a9fb8aa4b1e5e4a ?? i try it using string merkle = "4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b"; writeln(merkle.retro.text); and it gives me b33adedfa7b7212ba77cc2e37667f816f78cb13c88a81523a3f98baab4e1e5a4 Yeah. Angela did some messing around with Shadow Volume algorithms before she got into politics... :-) Cheers, A. Is not merkel is merkle, :P
[OT] Re: merkle reverse
On Thursday, 5 April 2018 at 08:12:38 UTC, aerto wrote: This is the bitcoin genesis block merkle root 4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b how i can get it at this format 3ba3edfd7a7b12b27ac72c3e67768f617fc81bc3888a51323a9fb8aa4b1e5e4a ?? i try it using string merkle = "4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b"; writeln(merkle.retro.text); and it gives me b33adedfa7b7212ba77cc2e37667f816f78cb13c88a81523a3f98baab4e1e5a4 Yeah. Angela did some messing around with Shadow Volume algorithms before she got into politics... :-) Cheers, A.
Re: merkle reverse
On Thursday, 5 April 2018 at 09:49:58 UTC, Seb wrote: Strings are bi-directional ranges, but they aren't random-access nor have a length chunks requires hasSlicing + hasLength: Okay, thanks for the great references. chunks/slide certainly need the length to decide which, and how many, elements to serve in the final chunk. The crucial part is now that an autodecoded string's final element can be determined in O(1) by looking at up to 4 code units from its un-decoded end, whereas its autodecoded length cannot be found in O(1). -- Simon
Re: merkle reverse
On Thursday, 5 April 2018 at 09:24:31 UTC, SimonN wrote: On Thursday, 5 April 2018 at 09:07:52 UTC, Seb wrote: FYI: The problem isn't chunks, but that strings aren't bi-directional ranges (hello ugly auto-decoding!). "4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b".byCodeUnit Thanks! Very appropriate because it's all hex digits anyway. Instead of std.experimental.all, one can also import std.utf. Initially, I wondered whether autodecoding was the issue here, but I dismissed it because the OP's example calls retro immediately on a string, which is supposedly not autodecodable as bi-directional. But I should examine retro's implementation because I remember several Phobos functions having special cases for strings (which is exactly the issue of auto-decoding). Well sorry for my poor words. Strings are bi-directional ranges, but they aren't random-access nor have a length which is typically required by other ranges to forward bidirectionality. chunks requires hasSlicing + hasLength: https://github.com/dlang/phobos/blob/193c61d985a9645014b2161b59ddb8692308e063/std/range/package.d#L7851 slide requires just hasSlicing: https://github.com/dlang/phobos/blob/193c61d985a9645014b2161b59ddb8692308e063/std/range/package.d#L8650 Now why does "aa"[0.. 1] work, but hasSlicing return false? Because it's explicitly excluded: https://github.com/dlang/phobos/blob/193c61d985a9645014b2161b59ddb8692308e063/std/range/primitives.d#L1557 tl;dr: if you want to do anything useful with strings, byCodeUnit is usually your best friend.
Re: merkle reverse
On Thursday, 5 April 2018 at 09:07:52 UTC, Seb wrote: FYI: The problem isn't chunks, but that strings aren't bi-directional ranges (hello ugly auto-decoding!). "4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b".byCodeUnit Thanks! Very appropriate because it's all hex digits anyway. Instead of std.experimental.all, one can also import std.utf. Initially, I wondered whether autodecoding was the issue here, but I dismissed it because the OP's example calls retro immediately on a string, which is supposedly not autodecodable as bi-directional. But I should examine retro's implementation because I remember several Phobos functions having special cases for strings (which is exactly the issue of auto-decoding). -- Simon
Re: merkle reverse
On Thursday, 5 April 2018 at 08:57:11 UTC, SimonN wrote:
On Thursday, 5 April 2018 at 08:12:38 UTC, aerto wrote:
This is the bitcoin genesis block merkle root
4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b how i can get it at this format 3ba3edfd7a7b12b27ac72c3e67768f617fc81bc3888a51323a9fb8aa4b1e5e4a ??
i try it using
string merkle =
"4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b";
writeln(merkle.retro.text); and it gives me
b33adedfa7b7212ba77cc2e37667f816f78cb13c88a81523a3f98baab4e1e5a4
Here's one solution with std.range.chunks. A small downside is
that it needs the array allocation in the middle because chunks
cannot offer the bi-directional range necessary for retro.
import std.range;
import std.algorithm;
void main()
{
string merkle =
"4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b";
assert (merkle.retro.equal(
"b33adedfa7b7212ba77cc2e37667f816f78cb13c88a81523a3f98baab4e1e5a4"));
assert (merkle.chunks(2).array.retro.joiner.equal(
"3ba3edfd7a7b12b27ac72c3e67768f617fc81bc3888a51323a9fb8aa4b1e5e4a"));
}
-- Simon
FYI: The problem isn't chunks, but that strings aren't
bi-directional ranges (hello ugly auto-decoding!).
Simply disable it with byCodeUnit:
---
import std.experimental.all;
void main()
{
"4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b".byCodeUnit.chunks(2).retro.joiner.writeln;
"4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b".byCodeUnit.slide(2, 2).retro.joiner.writeln;
}
---
Oh and the new slide is a generalization of chunks.
https://run.dlang.io/is/ggrh14
Re: merkle reverse
05.04.2018 11:57, SimonN пишет:
Here's one solution with std.range.chunks. A small downside is that it
needs the array allocation in the middle because chunks cannot offer the
bi-directional range necessary for retro.
import std.range;
import std.algorithm;
void main()
{
string merkle =
"4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b";
assert (merkle.retro.equal(
"b33adedfa7b7212ba77cc2e37667f816f78cb13c88a81523a3f98baab4e1e5a4"));
assert (merkle.chunks(2).array.retro.joiner.equal(
"3ba3edfd7a7b12b27ac72c3e67768f617fc81bc3888a51323a9fb8aa4b1e5e4a"));
}
-- Simon
It's a pity that retro can't work with chunks without array, it would be
really nice!
Re: merkle reverse
On Thursday, 5 April 2018 at 08:12:38 UTC, aerto wrote:
This is the bitcoin genesis block merkle root
4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b how i can get it at this format 3ba3edfd7a7b12b27ac72c3e67768f617fc81bc3888a51323a9fb8aa4b1e5e4a ??
i try it using
string merkle =
"4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b";
writeln(merkle.retro.text); and it gives me
b33adedfa7b7212ba77cc2e37667f816f78cb13c88a81523a3f98baab4e1e5a4
Here's one solution with std.range.chunks. A small downside is
that it needs the array allocation in the middle because chunks
cannot offer the bi-directional range necessary for retro.
import std.range;
import std.algorithm;
void main()
{
string merkle =
"4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b";
assert (merkle.retro.equal(
"b33adedfa7b7212ba77cc2e37667f816f78cb13c88a81523a3f98baab4e1e5a4"));
assert (merkle.chunks(2).array.retro.joiner.equal(
"3ba3edfd7a7b12b27ac72c3e67768f617fc81bc3888a51323a9fb8aa4b1e5e4a"));
}
-- Simon
