2,062 questions
6
votes
2
answers
81
views
How do I install the Raku Cro web framework using a dockerfile
I am attempting to wrap a Raku based web app in a dockerfile. I am using the Cro web framework but I cannot seem to install the Cro successfully.
I tried the dockerfile below:
# Use the official ...
- 91
7
votes
4
answers
227
views
"The Best Regex Trick" in Raku
The Best Regex Trick is about writing regexes that match r1 but not r2. The example they give is a regex that matches Tarzan (and "Tarzan and Jane") but not "Tarzan". After going ...
- 2,314
6
votes
1
answer
104
views
Unexpected flattening of arrays when initalizing an array
I'm not totally sure if this is a bug, a quirk, or simply a bad practice, but this is what happens:
[0] > my @nope = [["a","b"]]; @nope.push: ["b","c"]
[a b [...
- 23.4k
5
votes
1
answer
166
views
How can I make a functional chaining operator in Raku?
I a trying to translate this F# code to Raku for learning purposes:
type Meat = Chicken | Beef | Pork | Fish | Veggie
type Ingredient =
| Cheese | Rice | Beans | Salsa | Guacamole | SourCream | ...
- 7,501
6
votes
1
answer
128
views
Possible Bug with run as Last Statement in try Block
I don't know if this is a bug, or I just don't understand what's happening. If I have a run statement as the last statement in a try block, any error in the run statement is not caught. If it is not ...
- 1,189
10
votes
1
answer
174
views
Why DateTime.now and Date.today.DateTime have different timezone?
[23] > my $now = DateTime.now
2024-09-29T14:59:10.178051+08:00
[24] > my $eight-hours-later = Date.today.DateTime.later(:8hours)
2024-09-29T08:00:00Z
[25] > $now - $eight-hours-later
-3649....
- 821
7
votes
1
answer
153
views
When `whenever` block in `react` section starts processing events?
Let's say I have simple socket listening in one thread and I want to hold another thread until port is opened and socket is actually listening. Which one is correct:
Using do? Documentation of do ...
- 1,229
4
votes
1
answer
94
views
Defining bareword operators in Raku
I have some questions regarding defining bareword operators in Raku. As it stands in the language, there are a variety of bareword operators, such as div, mod, gcd, & lcm. As I'm curious about the ...
- 191
6
votes
2
answers
204
views
How should Regexes be passed to MAIN in Raku?
Is there an idiomatic way to pass a Regex from the command line to a Raku program. The following code accomplishes what I'm trying to do but it has a few issues (see below).
#!/bin/raku
use MONKEY-...
- 1,013
6
votes
1
answer
138
views
How can I use Raku Grammars with the comb function?
I would like to use Raku's comb function with a regex from a Grammar instead of a standalone regex. For example, in the following code, which parses journalctl logs from stdin, I would like to replace ...
- 1,013
6
votes
2
answers
111
views
How to override default content type in Cro::HTTP::Client?
I'm creating an object for making HTTP requests like this:
$!ua = Cro::HTTP::Client.new(
base-uri => 'https://what.ever/api/',
content-type => 'application/...
- 22.6k
6
votes
1
answer
104
views
How to do a multiple dispatch (or an alternative) for a single pair?
I really like the syntax of a pair :3melee which means melee => 3. I'd like to do the following:
my Creature $creature .= new(:fire-resist);
$creature.damage: :3melee;
$creature.damage: :3fire;
so ...
- 481
4
votes
1
answer
117
views
converting list of Str into list of Enums
I have an enum definition in a module AAA:
enum RDProcDebug <None All AstBlock BlockType Scoping Templates MarkUp>;
class Debug {
method foo(RDProcDebug @ds) {
for @ds { say .key ~ ' =>...
- 2,063
4
votes
2
answers
108
views
How to forward declare a role to be used for an enum?
Running this piece of code
use v6.d;
role DrawSurface { ... };
enum Surface does DrawSurface <Fire>;
role DrawSurface {
method draw () {
given self {
when Surface::...
- 481
4
votes
1
answer
118
views
Raku Actions Predicated on Parse Success?
Is there a way to configure Raku actions to only execute after a parse has completed successfully? For example, the program below outputs "Jane is telling us her age....", even with ...
- 11k
5
votes
1
answer
152
views
Partial matching in a simple Raku program
I've created a simple program based on the Raku parsefile example provided here. The contents of my Raku file are:
grammar Names {
token TOP { [<name><.ws>]+ }
token name { <:alpha&...
- 11k
3
votes
1
answer
76
views
looping through classes using require
I have a number of plugin classes each of which have a method 'enable'.
The following code works
unit class Top;
has $!rdp;
use Plugin::A;
use Plugin::B;
use Plugin::C;
submethod TWEAK {
my $rdp := ...
- 2,063
5
votes
1
answer
153
views
Raku: Using hyper or race with junctions
I have about 75000 files and I need to search each file for a set of key phrases stored in an array. I have Intel i9 capable of running 20 threads. I am trying to speed up the whole process by ...
- 5,749
5
votes
2
answers
180
views
Don't install a module if the operating system is Windows
Is it possible to write a META6.json file that
prints a message that the operating system is not supported
and does not try to install the module
if the operating system is Windows?
- 25k
3
votes
1
answer
96
views
How to set a named parameter to an exported sub when importing a module?
unit module My::Show;
sub show (:$indent = False) is export {
if $indent {
say " Showing with indentation.";
} else {
say "Showing without indentation.";...
- 1,815
13
votes
1
answer
595
views
What does the $¢ variable do in Raku?
The documentation says that there are only 3 special lexical variables ($_, $/, $!).
However, inspecting the MY:: pseudostash, it seems that a variable named $¢ also exists, and is undocumented (or at ...
- 133
2
votes
1
answer
129
views
How to get a seq of enum members filtering out some members
I have an enum list with actions and the members None and All. How do I create a sequence of enums that filters out None and All?
Test program in file filter-enum.raku:
#!/usr/bin/env raku
use v6.d;
...
- 2,063
6
votes
1
answer
89
views
Can a Range evaluate to False in Bool context in Raku?
While making use of a Range to solve a problem I noticed that a Range with 0 elems would be True as a Bool. In what scenarios could a Range be False?
[0] > (^0).so
True
[1] > (1..0).so
True
- 642
4
votes
2
answers
116
views
Raku module fails to work with Google Sheets .clear API function
Apologies for the long question. I am working on the raku Net::Google::Sheets module.
Currently it does a good job of successfully using OAuth2::Client::Google and getting and putting a 2D Array from/...
- 7,501
8
votes
1
answer
151
views
Breaking brace after the start keyword
This is the simple program, it prints a terminal size when you resize it:
#!/bin/env raku
use NCurses;
initscr;
loop {
given getch() {
when 27 { last } # exit when pressing esc
...
- 672
6
votes
1
answer
100
views
How can I dynamically export classes in raku?
I am updating a raku module (Physics::Measure)
My old code looks like this:
unit module Physics::Measure ...
class Length is Measure is export {}
class Mass is Measure is ...
- 7,501
8
votes
0
answers
117
views
cannot use `OUTER` as label name for loop control in Raku
If I use OUTA as a label name it works, but OUTER doesn't:
OUTA: say OUTA.^name; # Label
OUTER: say OUTER.^name; # OUTER
Thus:
OUTA: loop { last OUTA } # works
OUTER: loop { last OUTER } # fails (...
- 619
8
votes
1
answer
144
views
Is it possible to append subroutines to a Raku module at runtime?
I would like to be able to add a sub to a module Foo at runtime.
In Perl, I would do something like:
*{'My::Module::foo'} = \sub { 'FOO!' };
I know Raku doesn't have TypeGlobbing like Perl. Ideally ...
- 2,515
4
votes
3
answers
190
views
Why doesn't a Sequence get consumed when I assign it to an @var?
According to the class Seq docs:
A Seq is born in a state where iterating it will consume the values.
...
...
A Seq can also be constructed with the sequence operator ...
or one of its variants. ...
- 48.6k
3
votes
3
answers
147
views
TR/// : How do you apply TR to a string?
With tr///, I can do this:
my $str = 'xABCz';
$str ~~ tr:c/ABC//;
say "-->{$str}<--";
--output:--
-->ABC<--
But with TR///, which creates a new string, there doesn't seem to ...
- 48.6k
2
votes
3
answers
244
views
Regex word boundary: <|wb> v. <?wb>
Edit: @ikegami was the first person to respond and pointed out my typo.
The raku Regex docs say:
To match any word boundary, use <|w> or <?wb>. This is similar to \b in other languages.
...
- 48.6k
6
votes
1
answer
200
views
Raku exceptions: why are errors thrown sometime after the code that caused the errors?
This seems crazy to me:
use v6.d;
say "Before division by zero!";
my $result = divide(3, 0);
say "After division by zero!";
sub divide($a, $b) {
my $result;
$result = $a /...
- 48.6k
6
votes
2
answers
140
views
subset name of Any where Str|True: why does the name type match every type?
I expected the refinement of the Any type to Str|True would make the name type match any Str or True, but this is what I see:
subset name of Any where Str|True;
sub go(name :$x) {
say $x;
}
go(x =...
- 48.6k
7
votes
3
answers
187
views
Mapping a List with a Hash argument
In the docs for class List, it says:
routine map
multi method map(Hash:D \hash)
multi method map(Iterable:D \iterable)
multi method map(|c)
multi method map(\SELF: █; :$label, :$item) ...
- 48.6k
5
votes
1
answer
122
views
MAIN() function: how does multi-dispatch work?
Example 1:
#!/usr/bin/env raku
use v6.d;
sub MAIN(Int $int) {
say 'parameter $int: ', $int.^name;
}
--output:--
$ raku b.raku 10
parameter $int: IntStr
Example 2:
#!/usr/bin/env raku
use v6....
- 48.6k
8
votes
1
answer
142
views
How to make a Raku test optional if a module is not installed
I am adding a feature to a package that optionally uses DBIish. I would like to write a few unit tests to ensure that the functionality is working. However, DBIish should be an optional dependency, ...
- 2,515
-2
votes
1
answer
188
views
Which 'Perl Traps' have not been fixed in Raku? [closed]
Looking at Perl, I was very pleased to find a link to a section called "Perl Traps" in the perldocs. It represents a refreshing sense of honesty in an increasingly tech-hyped world.
The &...
- 2,289
5
votes
3
answers
206
views
Does Raku has a data type for encoding side effects as pure values?
I am doing some exercise from the book Grokking Functional Programming, the origin code examples are written in Scala, and I want to rewrite it with Raku.
In Scala's cats effect library, there is a ...
- 821
8
votes
1
answer
161
views
How do I get a &-conjoined regular expression to be considered as long a match as its constituents?
You can specify that a regular expression should only match if all its constituents match by using a conjunction, && or &:
[4] > 'ready' ~~ / r..dy & .ea.. /
｢ready｣
[5] > '...
- 4,311
13
votes
2
answers
438
views
Is it possible to use the index of an array in a map block?
I would like to use the index of the array in a map routine. For example, this Raku code:
raku -e 'my @a = "First", "Second", "Third", "First"; say @a.map({ &...
- 875
9
votes
1
answer
165
views
How, and how best, to select a method/sub based on a boolean?
I have a method in a class to return a hash, with the aim that children classes will over-ride the method. But for testing purposes, I want a different hash.
When the class is instantiated, I would ...
- 2,063
5
votes
2
answers
149
views
How to extract data from RakuAST 's
How best is it to extract a hash from the config portion of a RakuAST::Doc::Block ? Here is the program:
use v6.d;
use experimental :rakuast;
my $ast = Q:to/CONF/.AST;
=for rakudoc :category("...
- 2,063
7
votes
1
answer
147
views
Can't use sequence operator `...` on a separate line in Raku
The following code works:
my @fibo = 1, 1, -> $a, $b { $a + $b } ... *;
say @fibo[^10];
output:
(1 1 2 3 5 8 13 21 34 55)
But if you split this over multiple lines like this:
my @fibo = 1,
...
- 6,822
4
votes
1
answer
134
views
Confused about 'capturing'-behavior of ( ... ) e.g. "immutable lists" vs. [ ... ] e.g. "arrays"
I'm somewhat confused about the behavior of the following Raku program,
my @list;
my $v = 4;
@list.push: [ 1, $v ];
@list.push: ( 2, $v );
$v *= 2;
@list.push: [ 3, $v ];
@list.push: ( 4, $v );
$...
- 183
8
votes
2
answers
235
views
How do I find all possible values of an enum in Raku?
enum Direction <north east south west>;
for north, east, south, west -> $dir {
say $dir;
...
}
I don't want to repeat the list of Direction values here. How can I programmatically ...
- 6,822
5
votes
1
answer
113
views
List seems to be reused but bare value works fine
This:
my %dict;
my $counter = 0;
for ^5 -> $digit {
%dict{$digit} = ($counter,);
$counter += 1;
}
say %dict;
gives me this:
{0 => (5), 1 => (5), 2 => (5), 3 => (5), 4 =&...
- 329
5
votes
1
answer
91
views
Raku bug or feature: empty range is True
% raku
Welcome to Rakudo™ v2023.08.
Implementing the Raku® Programming Language v6.d.
Built on MoarVM version 2023.08.
To exit type 'exit' or '^D'
[0] > say so 1..0;
True
It would be useful if an ...
- 6,822
2
votes
2
answers
173
views
Is there an elegant way in Raku to see if two ranges overlap?
Is there an elegant way to see if two ranges have any overlap?
For instance, if
my $r = 1..10;
my $r1 = 2..5;
my $r2 = 7..15;
then $r1 ~~ $r is True. But $r ~~ $r1, $r2 ~~ $r, $r ~~ $r2 are all ...
- 6,822
5
votes
1
answer
146
views
Is it possible to lift a made value to Grammar TOP?
I have this raku Grammar:
#!/usr/bin/env raku
use v6.d;
use Grammar::Tracer;
grammar Grammar {
token TOP {
<city> \v
<state-zip> \v?
}
token city {
...
- 7,501
10
votes
1
answer
317
views
How to get the `< ... >` syntax on an object?
In Raku: when I create an object with a CALL-ME method, I would like to use the < ... > syntax for the signature instead of ( '...' ) when ... is a Str.
In the documentation, there is an example ...
- 2,063