Re: Problem with map, reduce, ..
On Wednesday, 24 June 2015 at 08:30:29 UTC, Adrian Matoga wrote: input.byLine() yields char[]'s as range elements, while props is (correctly) indexed by strings, i.e. immutable(char)[]. Ooops, more precisely it's because of the second argument of add() being string, but the solution above still applies.
Re: Problem with map, reduce, ..
On Wednesday, 24 June 2015 at 08:18:52 UTC, Stefan wrote:
I tried to refactor some existing code to use more of the
functional patterns/style (map, filter, reduce, ..).
The task is to read in some sort of a simple property file and
present the result as an associative array.
My attempt is:
import std.stdio;
import std.algorithm.iteration : filter, map, reduce;
import std.algorithm.mutation : split;
import std.string : indexOf, strip;
import std.stdio : File, writeln;
import std.algorithm : startsWith;
string[string] add( ref string[string] result, in string line) {
int assignmentIndex = indexOf( line, = );
if ( assignmentIndex 0 ) {
string key = line[ 0 .. assignmentIndex ];
string value = line[ assignmentIndex + 1 .. line.length
];
result[ key ] = value;
}
return result;
}
void main() {
auto input = File( test.ini, r );
auto lines = input.byLine()
.filter!( line = !startsWith( line, # )
!startsWith( line, !) line.length 0 )
.map!( line = strip( line ) );
string[string] props;
auto result = reduce!(add)( props, lines );
}
result should now contain the associative array.
However, it fails with an error in the reduce line:
c:\develop\dmd2.067.1\windows\bin\..\..\src\phobos\std\algorithm\iteration.d(2536):
Error: static assert Incompatible function/seed/element:
prop.add/string[string]/char[]
c:\develop\dmd2.067.1\windows\bin\..\..\src\phobos\std\algorithm\iteration.d(2521):
instantiated from here: reduceImpl!(false, MapResult!(__lambda2,
FilterResult!(__lambda1, ByLine!(char, char))), string[string])
c:\develop\dmd2.067.1\windows\bin\..\..\src\phobos\std\algorithm\iteration.d(2505):
instantiated from here: reducePreImpl!(MapResult!(__lambda2,
FilterResult!(__lambda1, ByLine!(char, char))), string[string])
source\prop.d(30):instantiated from here:
reduce!(string[string], MapResult!(__lambda2,
FilterResult!(__lambda1, ByLine!(char, char
I have no idea how to resolve this.
input.byLine() yields char[]'s as range elements, while props is
(correctly) indexed by strings, i.e. immutable(char)[]. Use .idup
to create an immutable copy of the property name, e.g.:
auto lines = input.byLine()
.filter!( line = !startsWith( line, # ) !startsWith(
line, !) line.length 0 )
.map!( line = strip( line.idup ) );
Re: Program exited with code -11
On Wednesday, 24 June 2015 at 06:54:57 UTC, weaselcat wrote: On Tuesday, 23 June 2015 at 06:50:28 UTC, Charles Hawkins wrote: On Tuesday, 23 June 2015 at 03:31:37 UTC, weaselcat wrote: On Tuesday, 23 June 2015 at 03:29:14 UTC, Charles Hawkins wrote: [...] Try to compile with either ldc or gdc and the -g flag, it should give you a backtrace. dmd seems to not like linux wrt backtraces. Thanks. I wish! I haven't had any success in compiling with anything but dub. gdc, dmd, rdmd always give me module mylib is in file 'mylib.d' which cannot be read on my import mylib; statement. I've tried every permutation of -I and -L that I can think of. It almost appears that one either uses dub for everything or nothing and I'm getting pretty frustrated with it as well. Perhaps I should just go back to old-fashioned make files? you can instruct dub to use other compilers with the --compiler option valid options include dmd,ldc,gdc,gdmd,ldmd Ah, a sort of hidden option. I've only been typing dub and thus, dub --help. Didn't think to do dub build --help. Is there a quick way to get gdc to recognize std.experimental.logger? I'm already spoiled by it. Choosing between it and a backtrace is difficult.
Re: cannot use UDA with same name as one of field's name
On Tuesday, 23 June 2015 at 23:52:52 UTC, Adam D. Ruppe wrote: On Tuesday, 23 June 2015 at 23:14:13 UTC, Steven Schveighoffer wrote: I'm not completely sure on the syntax, try adding some parens. Yeah, I'm pretty sure it needs to be @(full.name.here) void foo() Yep, something like this works. ``` @(vibe.data.serialization.name(_id)) int id; ``` But in this case `alias` looks better.
Re: Program exited with code -11
On Tuesday, 23 June 2015 at 06:50:28 UTC, Charles Hawkins wrote: On Tuesday, 23 June 2015 at 03:31:37 UTC, weaselcat wrote: On Tuesday, 23 June 2015 at 03:29:14 UTC, Charles Hawkins wrote: [...] Try to compile with either ldc or gdc and the -g flag, it should give you a backtrace. dmd seems to not like linux wrt backtraces. Thanks. I wish! I haven't had any success in compiling with anything but dub. gdc, dmd, rdmd always give me module mylib is in file 'mylib.d' which cannot be read on my import mylib; statement. I've tried every permutation of -I and -L that I can think of. It almost appears that one either uses dub for everything or nothing and I'm getting pretty frustrated with it as well. Perhaps I should just go back to old-fashioned make files? you can instruct dub to use other compilers with the --compiler option valid options include dmd,ldc,gdc,gdmd,ldmd
Problem with map, reduce, ..
I tried to refactor some existing code to use more of the
functional patterns/style (map, filter, reduce, ..).
The task is to read in some sort of a simple property file and
present the result as an associative array.
My attempt is:
import std.stdio;
import std.algorithm.iteration : filter, map, reduce;
import std.algorithm.mutation : split;
import std.string : indexOf, strip;
import std.stdio : File, writeln;
import std.algorithm : startsWith;
string[string] add( ref string[string] result, in string line) {
int assignmentIndex = indexOf( line, = );
if ( assignmentIndex 0 ) {
string key = line[ 0 .. assignmentIndex ];
string value = line[ assignmentIndex + 1 .. line.length ];
result[ key ] = value;
}
return result;
}
void main() {
auto input = File( test.ini, r );
auto lines = input.byLine()
.filter!( line = !startsWith( line, # ) !startsWith(
line, !) line.length 0 )
.map!( line = strip( line ) );
string[string] props;
auto result = reduce!(add)( props, lines );
}
result should now contain the associative array.
However, it fails with an error in the reduce line:
c:\develop\dmd2.067.1\windows\bin\..\..\src\phobos\std\algorithm\iteration.d(2536):
Error: static assert Incompatible function/seed/element:
prop.add/string[string]/char[]
c:\develop\dmd2.067.1\windows\bin\..\..\src\phobos\std\algorithm\iteration.d(2521):
instantiated from here: reduceImpl!(false, MapResult!(__lambda2,
FilterResult!(__lambda1, ByLine!(char, char))), string[string])
c:\develop\dmd2.067.1\windows\bin\..\..\src\phobos\std\algorithm\iteration.d(2505):
instantiated from here: reducePreImpl!(MapResult!(__lambda2,
FilterResult!(__lambda1, ByLine!(char, char))), string[string])
source\prop.d(30):instantiated from here:
reduce!(string[string], MapResult!(__lambda2,
FilterResult!(__lambda1, ByLine!(char, char
I have no idea how to resolve this.
Re: Problem with map, reduce, ..
On Wednesday, 24 June 2015 at 08:33:29 UTC, Adrian Matoga wrote: On Wednesday, 24 June 2015 at 08:30:29 UTC, Adrian Matoga wrote: input.byLine() yields char[]'s as range elements, while props is (correctly) indexed by strings, i.e. immutable(char)[]. Ooops, more precisely it's because of the second argument of add() being string, but the solution above still applies. Thanks! That does it! Any idea how to make the 'ugly' reduce step more 'pleasant'? I.e. make it a part of the filter, map, .. chain?
Re: Problem with map, reduce, ..
On Wednesday, 24 June 2015 at 09:35:35 UTC, Adrian Matoga wrote:
On Wednesday, 24 June 2015 at 08:58:10 UTC, Stefan wrote:
On Wednesday, 24 June 2015 at 08:33:29 UTC, Adrian Matoga
wrote:
[...]
Thanks! That does it!
Any idea how to make the 'ugly' reduce step more 'pleasant'?
I.e. make it a part of the filter, map, .. chain?
What about:
auto result = File(test.ini, r)
.byLine()
.filter!( line = !startsWith( line, # )
!startsWith( line, !) line.length 0 )
.map!( line = line.idup.split('='))
.filter!( fields = fields.length 1)
.map!( fields = tuple(fields[0].strip(),
fields[1].strip() ))
.assocArray();
Wow! Very cool!
Thanks
Re: kill and thisProcessID
On Wednesday, 24 June 2015 at 11:39:51 UTC, Nordlöw wrote: What to do? See also: Discussion at http://dlang.org/library/std/process/kill.html
Re: kill and thisProcessID
On 6/24/15 7:39 AM, Nordlöw wrote: I have a process that shall suspend itself using SIGTSTP or SIGSTOP. My current plan is import std.process: thisProcessID, kill, Pid; import core.sys.posix.signal: SIGKILL, SIGSTOP, SIGTSTP; const thisPid = thisProcessID; // some call to kill() but kill() needs a `Pid` so kill(thisPid, SIGTSTP); fails and constructing Pid cannot be done because kill(new Pid(thisPid), SIGTSTP); errors as Error: class std.process.Pid member this is not accessible What to do? Why not use core.sys.posix.signal: kill instead? You're already importing the module anyway. -Steve
Re: Problem with map, reduce, ..
On Wednesday, 24 June 2015 at 08:58:10 UTC, Stefan wrote:
On Wednesday, 24 June 2015 at 08:33:29 UTC, Adrian Matoga wrote:
On Wednesday, 24 June 2015 at 08:30:29 UTC, Adrian Matoga
wrote:
input.byLine() yields char[]'s as range elements, while props
is (correctly) indexed by strings, i.e. immutable(char)[].
Ooops, more precisely it's because of the second argument of
add() being string, but the solution above still applies.
Thanks! That does it!
Any idea how to make the 'ugly' reduce step more 'pleasant'?
I.e. make it a part of the filter, map, .. chain?
What about:
auto result = File(test.ini, r)
.byLine()
.filter!( line = !startsWith( line, # ) !startsWith(
line, !) line.length 0 )
.map!( line = line.idup.split('='))
.filter!( fields = fields.length 1)
.map!( fields = tuple(fields[0].strip(), fields[1].strip()
))
.assocArray();
Re: kill and thisProcessID
On Wednesday, 24 June 2015 at 11:39:51 UTC, Nordlöw wrote: I have a process that shall suspend itself using SIGTSTP or SIGSTOP. My current plan is import std.process: thisProcessID, kill, Pid; import core.sys.posix.signal: SIGKILL, SIGSTOP, SIGTSTP; const thisPid = thisProcessID; // some call to kill() but kill() needs a `Pid` so kill(thisPid, SIGTSTP); fails and constructing Pid cannot be done because kill(new Pid(thisPid), SIGTSTP); errors as Error: class std.process.Pid member this is not accessible What to do? in std.process, add a `kill()` overload that takes `thisPid` as argument, it will create the `Pid` as a local scoped instance and it will call the normal `kill()` version that takes a Pid as argument with the scoped `Pid` instance. propose a PR for this overloaded `kill()` and wait dmd 2.068 release. Pid is well locked BTW: private constructor, final class...
kill and thisProcessID
I have a process that shall suspend itself using SIGTSTP or SIGSTOP. My current plan is import std.process: thisProcessID, kill, Pid; import core.sys.posix.signal: SIGKILL, SIGSTOP, SIGTSTP; const thisPid = thisProcessID; // some call to kill() but kill() needs a `Pid` so kill(thisPid, SIGTSTP); fails and constructing Pid cannot be done because kill(new Pid(thisPid), SIGTSTP); errors as Error: class std.process.Pid member this is not accessible What to do?
Re: kill and thisProcessID
On Wednesday, 24 June 2015 at 11:39:51 UTC, Nordlöw wrote: What to do? I believe the best solution is to add a new function Pid thisProcessPid() to std.process and refer to this from kill(Pid). Should I do PR?
Re: Compiles but does not link
On Thursday, 25 June 2015 at 00:24:23 UTC, Paul D Anderson wrote:
The code snippet below compiles but the linker fails with Error
42: Symbol undefined.
What am I doing wrong?
void main()
{
int foo(int a);
alias FP = int delegate(int);
FP fp = foo;
}
Paul
Uh, never mind. I got so focused on the delegate I forgot to give
the function a body.
Re: core.exception.InvalidMemoryOperationError@(0) on File Reading.
On Tuesday, 23 June 2015 at 18:49:59 UTC, David DeWitt wrote: On Monday, 22 June 2015 at 20:30:40 UTC, David DeWitt wrote: I am getting an core.exception.InvalidMemoryOperationError@(0) auto recs = f // Open for reading .byLineCopy(); .array; //Here is where is appears to be happening. [...] I have had a chance to try the new phobos. Dealing with the errors related to: http://forum.dlang.org/thread/mm1fdo$q5u$1...@digitalmars.com in debian. Gonna mess with it some more when I have a chance. I pulled down the latest version on Github and everything ran fine.
Compiles but does not link
The code snippet below compiles but the linker fails with Error
42: Symbol undefined.
What am I doing wrong?
void main()
{
int foo(int a);
alias FP = int delegate(int);
FP fp = foo;
}
Paul
Casting from an enum type to another enum type
Hi!
What is the straightest way to safely cast from one enum type A
to another enum type B, when B, in terms of values as well as
identifiers, is a strict subset of A?
Ideally, that should be as simple as to!B(a). So far I've tried
a couple of things, and one way I found was to first cast A to
int, then cast that to B, but that is not really straightforward.
Example:
import std.stdio;
import std.conv;
enum Color { r, o, y, g, b, i, v }
enum StyleColor : int { o = Color.o, b = Color.b }
void main()
{
auto c = Color.g;
// Problem: the result is not guaranteed to be a StyleColor.
// Does not throw, needs extra checks.
auto d1 = cast(StyleColor) c;
// Typesafe, but is not exactly straightforward.
auto d2 = to!StyleColor(cast(int) c);
// Error: template std.conv.toImpl cannot deduce
// function from argument types !(StyleColor)(Color)
//
// Changing enum StyleColor : Color to enum StyleColor :
int
// in the definition above does not help either.
auto d3 = to!StyleColor(c);
}
Template mixin can not introduce overloads
Is this intended or is it a bug?
void main(string[] args)
{
Test a;
a.foo(5); // Fails to compile
}
struct Test
{
mixin testMix;
void foo(string y){}
}
mixin template testMix()
{
void foo(int x){}
}
Suggested enhancements/changes to D
Is there a place where these should be posted for discussion?
Re: Suggested enhancements/changes to D
On Wednesday, 24 June 2015 at 16:44:06 UTC, DLearner wrote: Is there a place where these should be posted for discussion? The general forum: http://forum.dlang.org/group/general
Re: Program exited with code -11
On Wednesday, 24 June 2015 at 07:52:10 UTC, Charles Hawkins wrote: On Wednesday, 24 June 2015 at 06:54:57 UTC, weaselcat wrote: On Tuesday, 23 June 2015 at 06:50:28 UTC, Charles Hawkins wrote: [...] you can instruct dub to use other compilers with the --compiler option valid options include dmd,ldc,gdc,gdmd,ldmd Ah, a sort of hidden option. I've only been typing dub and thus, dub --help. Didn't think to do dub build --help. Is there a quick way to get gdc to recognize std.experimental.logger? I'm already spoiled by it. Choosing between it and a backtrace is difficult. I believe it's available as a dub package albeit outdated, should be roughly similar though.
Filtering Associative Array Key-Values the D way
I'm trying to understand filtering an Associative Array the D
way. I have the code below
(Using while readln cause problem failing on Debian using
byLineCopy()). When the byKeyValue().filter evaluates to reduce
the number of Keys:Values to only the ones in the filtered
header, what is the best way to transform the Pair back to an AA
instead of having to run the foreach loop after? Basically if
the file has 300 columns and 300 in the full header but only 15
in the filtered header I want the return of rec to only be the 15
in an Associative Array. Thanks :)
string line;
string[string][] records;
while ((line = f.readln()) !is null){
string[string] record;
auto rec = assocArray(zip(h1.fullHeader,
splitter(line,',')))
.byKeyValue().filter!(a=h1.filteredHeader.canFind(a.key));
foreach(r;rec){
record[r.key] = r.value;
}
records ~= record;
}
Re: Template mixin can not introduce overloads
On Thursday, 25 June 2015 at 03:49:04 UTC, Tofu Ninja wrote:
Is this intended or is it a bug?
Intended, the mixin template works on the basis of names. This
means that you can override methods from the mixin by writing a
member with the same name - very useful thing - but also means no
overloading happens without an extra step.
The extra step is easy though: alias the name in:
void main(string[] args)
{
Test a;
a.foo(5); // works!
a.foo(4qsda);
}
struct Test
{
mixin testMix tm; // give it a name to reference later
void foo(string y){}
alias tm.foo foo; // alias the mixin thing too
}
mixin template testMix()
{
void foo(int x){}
}
By adding that explicit alias, it tells the compiler that yes,
you do want it added to the set, not completely overridden by
your replacement method.
function default parameters lost
I'm trying to pass a function pointer while keeping the default
parameter values intact. Given the following:
import std.traits;
import std.stdio;
int foo(int a, int b = 1)
{
return a;
}
alias FOOP = int function(int, int = 1);
struct ST(POOF)
{
FOOP fctn;
this(POOF fctn)
{
this.fctn = fctn;
}
void details()
{
alias PDVA = ParameterDefaultValueTuple!fctn;
writefln(typeid(PDVA[0]) = %s, typeid(PDVA[0]));
writefln(typeid(PDVA[1]) = %s, typeid(PDVA[1]));
}
}
void main()
{
FOOP fp = foo;
auto st = ST!FOOP(fp);
st.details;
}
The default parameter value types are void, int: a has no default
and b has an int value as its default.
If I change line 14 from
FOOP fctn;
to
POOF fctn;
The default parameter value types are void, void. In other words
the default value for b is no longer there.
Why doesn't invoking the template (ST!FOOP) replace POOF in line
14 with FOOP?
Paul
Re: Casting from an enum type to another enum type
On Wednesday, 24 June 2015 at 15:29:03 UTC, Roland Hadinger wrote:
Hi!
What is the straightest way to safely cast from one enum type A
to another enum type B, when B, in terms of values as well as
identifiers, is a strict subset of A?
Ideally, that should be as simple as to!B(a). So far I've
tried a couple of things, and one way I found was to first cast
A to int, then cast that to B, but that is not really
straightforward.
Example:
import std.stdio;
import std.conv;
enum Color { r, o, y, g, b, i, v }
enum StyleColor : int { o = Color.o, b = Color.b }
void main()
{
auto c = Color.g;
// Problem: the result is not guaranteed to be a StyleColor.
// Does not throw, needs extra checks.
auto d1 = cast(StyleColor) c;
// Typesafe, but is not exactly straightforward.
auto d2 = to!StyleColor(cast(int) c);
// Error: template std.conv.toImpl cannot deduce
// function from argument types !(StyleColor)(Color)
//
// Changing enum StyleColor : Color to enum StyleColor :
int
// in the definition above does not help either.
auto d3 = to!StyleColor(c);
}
std.conv.to really should be able to do this, but I guess not
many people have needed to do this. You can write an extension
to `to` which does it for you:
import std.traits;
auto to(To, From)(From f)
if (is(From == enum) is(To == enum) is(OriginalType!From :
OriginalType!To))
{
return cast(To)f;
}
enum Color { r, o, y, g, b, i, v }
enum StyleColor : int { o = Color.o, b = Color.b }
void main()
{
auto c = Color.g;
auto s = c.to!StyleColor;
}
Re: Casting from an enum type to another enum type
Note that this is a very simple example. You need to check in the function that a valid StyleColor will actually be produced. Otherwise, it'll happily produce a StyleColor that's invalid.
Re: Filtering Associative Array Key-Values the D way
On 06/24/2015 09:08 AM, David DeWitt wrote:
I'm trying to understand filtering an Associative Array the D way. I
have the code below
(Using while readln cause problem failing on Debian using
byLineCopy()). When the byKeyValue().filter evaluates to reduce the
number of Keys:Values to only the ones in the filtered header, what is
the best way to transform the Pair back to an AA instead of having to
run the foreach loop after? Basically if the file has 300 columns and
300 in the full header but only 15 in the filtered header I want the
return of rec to only be the 15 in an Associative Array. Thanks :)
string line;
string[string][] records;
while ((line = f.readln()) !is null){
string[string] record;
auto rec = assocArray(zip(h1.fullHeader, splitter(line,',')))
.byKeyValue().filter!(a=h1.filteredHeader.canFind(a.key));
foreach(r;rec){
record[r.key] = r.value;
}
records ~= record;
}
It would be more efficient to filter the input before creating a larger
AA to be thrown away:
import std.stdio;
import std.range;
import std.algorithm;
void main()
{
auto keys = 10.iota;
auto values = keys.map!(k = 10 * k);
auto result = zip(keys, values)
.filter!(t = t[0] % 2)
.assocArray;
writefln(%(%s: %s\n%), result);
}
The AA contains elements with odd keys:
1: 10
5: 50
9: 90
3: 30
7: 70
Ali
Re: Check if template has been passed a reference type or value type?
On Sunday, 7 June 2015 at 15:39:17 UTC, Marc Schütz wrote:
On Sunday, 7 June 2015 at 15:17:27 UTC, 1967 wrote:
I've got a template that takes in a type. Sometimes the type
is a class, sometimes a struct, sometimes just an int. It
doesn't much matter what it is, but if it's a reference type I
need to check if it's null so I can make it not null before
using it. I get an error if I try to check if a value type is
null so I'd like to put a static if to check if the type
passed to the template is a nullable one so I can avoid
checking the value types passed in. What do I have to do to
check for nullability?
You can directly check whether it allows comparison with null:
static if(is(typeof(value is null) : bool)) {
if(value is null)
...
}
Don't forget [`Nullable`][0] type, which won't pass this check.
[0]: http://dlang.org/phobos/std_typecons.html#.Nullable
Re: Casting from an enum type to another enum type
On Wednesday, 24 June 2015 at 18:16:42 UTC, Meta wrote:
std.conv.to really should be able to do this, but I guess not
many people have needed to do this. You can write an
extension to `to` which does it for you:
import std.traits;
auto to(To, From)(From f)
if (is(From == enum) is(To == enum) is(OriginalType!From
: OriginalType!To))
{
return cast(To)f;
}
Thanks, that works!
I'll add this to my project's 'helpers' module, with the return
line replaced by:
foreach (m; EnumMembers!To) {
if (m == f)
return m;
}
throw new ConvException(Value not in enum);
