www.digitalmars.com         C & C++   DMDScript  

digitalmars.D.bugs - [Issue 6023] New: std.random.uniform and std.bigint.BigInt compilation error

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=6023

           Summary: std.random.uniform and std.bigint.BigInt compilation
                    error
           Product: D
           Version: D2
          Platform: Other
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Phobos
        AssignedTo: nobody puremagic.com
        ReportedBy: dpx.infinity gmail.com



22:00:21 PDT ---
uniform function from standard library doesn't work correctly with standard
BigInt. There are no indications anywhere that it shouldn't work, so I think it
is a bug.
Code sample:

import std.stdio;
import std.bigint;
import std.random;

void main() {
    BigInt x = uniform!"[]"(BigInt(1), BigInt(1000));
    writefln("%s", x);
}

Compilation error:
/usr/include/d/dmd/phobos/std/conv.d(322): Error: function
std.bigint.BigInt.toString (void delegate(const(char)[]) sink, string
formatString) const is not callable using argument types ()
/usr/include/d/dmd/phobos/std/conv.d(322): Error: expected 2 function
arguments, not 0

Linux i686, dmd 2.052

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
May 16 2011
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=6023


Paul D. Anderson <paul.d.anderson comcast.net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |paul.d.anderson comcast.net



13:21:45 PDT ---
The error message is the one returned when std.conv.to!string(BigInt) is
called.

std.bigint doesn't support std.conv.to!string. (You know all about this from
5231.) This has been reported several times already.

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
Jun 10 2011
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=6023




23:48:18 PDT ---

 The error message is the one returned when std.conv.to!string(BigInt) is
 called.
 
 std.bigint doesn't support std.conv.to!string. (You know all about this from
 5231.) This has been reported several times already.
Yes, I know. But isn't it strange that the standard library is inconsistent with itself? Shouldn't decisions like "remove a function which other parts of library expect to be" be more deliberate? I haven't seen such problems in any of the languages I used, and I think it is not good for the language itself to have them. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 10 2011
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=6023


Don <clugdbug yahoo.com.au> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |clugdbug yahoo.com.au




 The error message is the one returned when std.conv.to!string(BigInt) is
 called.
 
 std.bigint doesn't support std.conv.to!string. (You know all about this from
 5231.) This has been reported several times already.
More accurately, to!string doesn't support std.bigint. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 11 2011
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=6023




Original sample code cannot yet compile, but error messages are different.

C:\dmd2\src\phobos\std\random.d(1045): Error: template std.random.uniform does
not match any function template declaration
C:\dmd2\src\phobos\std\random.d(1043): Error: template std.random.uniform
cannot deduce template function from argument types
!("[]",igInt,BigInt,MersenneTwisterEngine!(uint,32,624,397,31,-1727483681u,11,7,-1658038656u,15,-272236544u,18))(BigInt,BigInt,MersenneTwistrEngine!(uint,32,624,397,31,-1727483681u,11,7,-1658038656u,15,-272236544u,18))
C:\dmd2\src\phobos\std\random.d(1045): Error: template instance
uniform!("[]",BigInt,BigInt,MersenneTwisterEngine!(uint,32,624,397,31-1727483681u,11,7,-1658038656u,15,-272236544u,18))
errors instantiating template
test.d(8): Error: template instance std.random.uniform!("[]",BigInt,BigInt)
error instantiating
test.d(8): Error: template std.bigint.BigInt.__ctor does not match any function
template declaration
C:\dmd2\src\phobos\std\bigint.d(82): Error: template std.bigint.BigInt.__ctor
cannot deduce template function from argument types !()_error_)

Because BigInt type is not integral.

  import std.traits;
  pragma(msg, isIntegral!BigInt);  // pritns false

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
May 19 2012
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=6023






 
 Because BigInt type is not integral.
 
   import std.traits;
   pragma(msg, isIntegral!BigInt);  // pritns false
Maybe we'll need to add to std.traits a new trait that's true for all integral values, BigInts too.
It's a bit difficult. If BigInt used the same algorithm for random number generation that built-in ints use, the performance would be horrible. For an n-byte number, you'd have O(2n) memory allocations on average, with an unbounded worst case, instead of the single allocation you'd have with a dedicated algorithm. And generating a string of 1 million random bits is the sort of thing that somebody is likely to do. Supporting it with terrible performance isn't any better than not supporting it at all. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 21 2012
prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=6023


Joseph Rushton Wakeling <joseph.wakeling webdrake.net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |joseph.wakeling webdrake.ne
                   |                            |t



2013-08-30 04:41:06 PDT ---

 uniform function from standard library doesn't work correctly with standard
 BigInt. There are no indications anywhere that it shouldn't work, so I think
it is a bug.
Typical existing RNGs may be expected to have an underlying range of 0 .. uint.max, with others perhaps extending that to ulong.max. They inherently can't cover the range of possible values that a BigInt can be expected to take, so there's a strong potential for statistical problems (albeit that those maxima are Very Big Indeed). It might be possible to do some customization so that BigInts falling within the appropriate bounds can be used -- probably your best bet would be to convert to uints, call the integral-type uniform() and convert back -- but in general generating random BigInts would require a BigInt-dedicated RNG. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Aug 30 2013