| Hydrazer | why does kv method not return list of list but just list | 02:09 | |
| seems a lot more convenient that way | 02:13 | ||
| SmokeMachine | You can have it returning a list ou pairs if you want that that way… a list with key and values flat is convenient because you can have more than 1 argument being received by a block… | 02:21 | |
| m: my %a = :1a, :2b, :3c; for %a.kv -> $a, $b { say “$a => $b” } | 02:22 | ||
| camelia | c => 3 a => 1 b => 2 |
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| SmokeMachine | Hydrazer 👆 | 02:23 | |
| Hydrazer | ok | 02:24 | |
| if I have a word “chicken” and a substring “ekc” is there a better way of getting the reverse index of the string than ‘$len - 1 - $str.flip.index(“ekc”)’ | 04:28 | ||
| if I have a word “chicken” and a substring “ekc” is there a better way of getting the reverse index of the string than $len - 1 - $str.flip.index(“ekc”) | |||
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| samebchase | m: (1, -> $a { $a + 1 } ... *)[^7]; | 06:17 | |
| camelia | ( no output ) | ||
| samebchase | m: say (1, -> $a { $a + 1 } ... *)[^7]; | ||
| camelia | (1 2 3 4 5 6 7) | ||
| samebchase | , but | ||
| m: say ((DateTime.new(:2021year, :11month, :30day), -> $a { $a + Duration.new(:1days) } ... *)[^7]) | |||
| camelia | (2021-11-30T00:00:00Z 2021-11-30T00:00:00Z 2021-11-30T00:00:00Z 2021-11-30T00:00:00Z 2021-11-30T00:00:00Z 2021-11-30T00:00:00Z 2021-11-30T00:00:00Z) | ||
| samebchase | this is returning the same date, how do I get a sequence of dates? | ||
| something to do with referencing the same object repeatedly or whatever? | 06:19 | ||
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| lizmat | Hydrazer: there's also .rindex | 10:32 | |
| Nemokosch | but it doesn't revert the string, right? | 10:42 | |
| lizmat | no, it doesn't, it just searches from the end | ||
| so if you're have multiple occurrences, you'd get the last one | |||
| Nemokosch | yeah well, the intended behavior of this "ekc" lookup in "chicken" isn't fully clear to me | 10:44 | |
| SmokeMachine | m: say "chicken".rindex: "eck": .flip | 11:48 | |
| camelia | No such method 'flip' for invocant of type 'Any'. Did you mean any of these: 'Slip', 'flat', 'skip'? in block <unit> at <tmp> line 1 |
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| SmokeMachine | m: say "chicken".rindex: "ekc".flip | ||
| camelia | 3 | ||
| SmokeMachine | Hydrazer: like this 👆? | 11:50 | |
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| Hydrazer | no i should be 3 as it is checking backwards | 14:17 | |
| no i should be 1 as it is checking backwards | |||
| like index of the start of the word unflipped | |||
| also is there a better way to check for not nil than ```pl | |||
| if !$var ~~ Nil | |||
| ``` | |||
| also is there a better way to check for not nil than ```pl | 14:18 | ||
| if !($var ~~ Nil) | |||
| ``` | |||
| lakmatiol | you could do `$var !~~ Nil`, but I feel like there is bound to be something better you can do here | 14:23 | |
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| qorg11 | m: say 3; | 15:39 | |
| camelia | 3 | ||
| qorg11 | m: my $fh = open "/etc/passwd"; say $fh.lines | 15:43 | |
| camelia | (bin:x:1:1:bin:/bin:/bin/bash daemon:x:2:2:Daemon:/sbin:/bin/bash ftp:x:40:49:FTP account:/srv/ftp:/bin/bash games:x:12:100:Games account:/var/games:/bin/bash lp:x:4:7:Printing daemon:/var/spool/lpd:/bin/bash mail:x:8:12:Mailer daemon:/var/spool/clien… | ||
| qorg11 | ha | ||
| getimiskon | huh | 15:44 | |
| qorg11 | m: (1..1000).map: -> $i { say $i} | ||
| camelia | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 … |
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| qorg11 | m: say "hello world"; | 15:46 | |
| camelia | hello world | ||
| qorg11 | m: use NCurses; | 15:51 | |
| camelia | 5===SORRY!5=== Error while compiling <tmp> Could not find NCurses in: inst#/home/camelia/.raku inst#/home/camelia/rakudo-m-inst-2/share/perl6/site inst#/home/camelia/rakudo-m-inst-2/share/perl6/vendor inst#/home/camelia/r… |
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| qorg11 | m: run "ls" | 15:52 | |
| camelia | Inline-Perl5 Perlito bin dalek-queue evalbot file.txt lib log mbox nqp-js p1 p2 perl5 precomp rakudo-j-1 rakudo-j-2 rakudo-j-inst rakudo-j-inst-1 rakudo-j-inst-2 rakudo-m-1 rakudo-m-2 rakudo-m-inst rakudo-m-… |
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| lizmat | m: my $fh = open "/etc/shadow"; say $fh.lines # that would worry me | 16:03 | |
| camelia | Failed to open file /etc/shadow: Permission denied in block <unit> at <tmp> line 1 |
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| A26F64 | m: my $i = Nil; $i ~~ Nil; | 17:15 | |
| camelia | ( no output ) | ||
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| lizmat | A26F64: Nil will make $i turn to its default state, which would be Any | 17:39 | |
| m: my $i = Nil; say $i ~~ Nil | |||
| camelia | False | ||
| qorg11 | m: run "ls -la" | ||
| camelia | The spawned command 'ls -la' exited unsuccessfully (exit code: 1, signal: 0) in block <unit> at <tmp> line 1 |
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| lizmat | m: my $i is defailt(Nil) = Nil; say $i ~~ Nil | ||
| camelia | 5===SORRY!5=== Error while compiling <tmp> Can't use unknown trait 'is' -> 'defailt' in a variable declaration. at <tmp>:1 ------> 3my $i is defailt(Nil)7⏏5 = Nil; say $i ~~ Nil expecting any of: TypeObject de… |
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| lizmat | m: my $i is default(Nil) = Nil; say $i ~~ Nil | ||
| camelia | True | ||
| qorg11 | m: fork | ||
| camelia | 5===SORRY!5=== Error while compiling <tmp> Undeclared routine: fork used at line 1 |
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| lizmat | qorg11: what are you trying to achieve ? | 17:40 | |
| qorg11 | m: use NativeCall; sub fork( --> int32) is native("c",v6) {*}; fork(); | ||
| camelia | ( no output ) | ||
| qorg11 | lizmat: idk just messing with it | ||
| lizmat | but why online / on Camelia, and not locally ? | ||
| qorg11 | because i want to see what happens to the bot | 17:41 | |
| when doing weird thigns such as forking | |||
| lizmat | still not sure why you'd want to do that to the bot that is providing a service | 17:42 | |
| A26F64 | @lizmat: The best way to test a scalar explicitly for Nil, then, would be `$i.defined`? | 17:43 | |
| lizmat | well, why would you want to check for Nil specifically in the first place ? | 17:44 | |
| feels to me you're trying to solve something but are asking the wrong question ? | 17:45 | ||
| if you really want to check for Nil, then probably =:= Nil would be the quickest | |||
| A26F64 | It seems like an ordinary expectation. A function, say, might return an object if an appropriate one is found; we want to know if that is not the case. Nil seems like a not-unreasonable return value in that situation. | 17:47 | |
| I suppose that it could return False. | 17:48 | ||
| lizmat | well, there's different ways of looking at that | ||
| if a sub is supposed to return a Foo object, but it cannot for some reason, and you don't want to throw | 17:49 | ||
| you can return a Failure | |||
| A26F64 | ("found" above meaning, by the way, simply that the function is trying to produce an object from some underlying data or criteria.) | ||
| lizmat | m: sub a($a) { fail "Sorry, the wrong answer" if $a != 42 }; if a(666) { say "success" } | 17:50 | |
| camelia | ( no output ) | ||
| lizmat | m: sub a($a) { fail "Sorry, the wrong answer" if $a != 42 }; if a(42) { say "success" } | ||
| camelia | ( no output ) | ||
| A26F64 | In this case it might be reasonable to not have produced a Foo object and we would just like to proceed accordingly. Would Failure really be appropriate? It's not technically an exception or failure. | 17:51 | |
| lizmat | m: sub a($a) { fail "Sorry, the wrong answer" if $a != 42; $a }; if a(42) { say "success" } | ||
| camelia | success | ||
| A26F64 | The variable to which the function output is being assigned may expect a particular type, though, right? | 18:04 | |
| m: sub a($a) { fail "Sorry, the wrong answer" if $a != 42; $a }; my Int $result = a(666); | |||
| camelia | Earlier failure: Sorry, the wrong answer in sub a at <tmp> line 1 in block <unit> at <tmp> line 1 Final error: Type check failed in assignment to $result; expected Int but got Failure (Failure.new(exceptio...) in block <unit> at… |
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| lizmat | A26F64: indeed, and then it will bomb | 18:11 | |
| m: sub a($a) { $a != 42 ?? Nil !! $a }; my Int $a = a(666); say $a | 18:12 | ||
| camelia | (Int) | ||
| lizmat | in that sense, you could see Nil as a soft failure | ||
| m: sub a($a) { fail "Sorry, the wrong answer" if $a != 42; $a }; if a(666) { say "success" } # note that this does **not** bomb | 18:13 | ||
| camelia | ( no output ) | ||
| lizmat | m: sub a($a) { fail "Sorry, the wrong answer" if $a != 42; $a }; if a(666) { say "success" } else { say "sorry, that failed" } | ||
| camelia | sorry, that failed | ||
| gfldex | A26F64: Nil indicates the absense of a value. We us it for Routines that semantically can't possibly return a value. Yet, they mast be able to return Failure-objects so we are able to pass on Exception objects from a child thread to the parent thread. That is the reason why Failure is a subclass of Nil. | 18:18 | |
| A26F64 | And Nil in the case that I described is indeed essentially the absence of a value and something of a "soft failure". But I shall experiment further with that and with `fail` in this case. | 18:25 | |
| lizmat | "fail" give you the possibility to add information about *why* it is failing | 18:26 | |
| also note that essentially, "fail" is like "return", so you drop out of the sub immediately | 18:27 | ||
| and yet another Rakudo Weekly News hits the Net: rakudoweekly.blog/2021/11/29/2021-...sdem-2022/ | 18:33 | ||
| gfldex | A26F64: If you want a special value as a marker, you can subclass Nil: gfldex.wordpress.com/2021/04/27/th...-a-riddle/ | ||
| lizmat | that feels... too advanced for a beginner ? | 18:34 | |
| gfldex | What doesn't? :-> The docs don't really explain how we handle defineness and exceptions. It's one of those places where to many concepts come together in Raku to DWIM. | 18:36 | |
| lizmat | subclassing Nil :-) | ||
| A26F64 | One other (hopefully) novice and explicit (as opposed to my earlier implicit) question: can we specify the type of a List's elements in any way? You can of course do so for an Array: `my Int @foo = [4, 2]`. | 18:40 | |
| lizmat | no, you cannot do that for List, as Lists do not have a descriptor | 18:41 | |
| that's the internal object that keeps what is allowed on an Array and a Hash | 18:42 | ||
| List and Map don't have that | |||
| A26F64 | I thought more or less so. I was wondering about that not just for regular code but also for class attributes. | 18:44 | |
| An attribute might need to be a Positional of some sort but I might not need it to be an Array. | 18:45 | ||
| lizmat | m: my @a is List = 1,2,3; dd @a | ||
| camelia | (1, 2, 3) | ||
| gfldex | m: class C { has Positional $.pos }; C.new(:pos(1,2,3)); | 18:46 | |
| camelia | ( no output ) | ||
| lizmat | m: class A { has @.foo is List }; dd A.new( foo => 1,2,3 ) | ||
| camelia | Default constructor for 'A' only takes named arguments in block <unit> at <tmp> line 1 |
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| lizmat | m: class A { has @.foo is List }; dd A.new( foo => (1,2,3) ) | ||
| camelia | A.new(foo => (1, 2, 3)) | ||
| gfldex | A26F64: the @ following a declarator and in front of an identifier means "Positional". | 18:47 | |
| A26F64 | lizmat But that isn't allowing type restrictions on the individual elements, which you could do with Arrays. . . . | 18:48 | |
| gfldex | Is a signature the declarator is implicit. | ||
| A26F64 | class A { has Int @.foo is List }; dd A.new( foo => (1,'string',3) ) | ||
| m: class A { has Int @.foo is List }; dd A.new( foo => (1,'string',3) ) | |||
| camelia | 5===SORRY!5=== Error while compiling <tmp> List cannot be parameterized at <tmp>:1 ------> 3class A { has Int @.foo is List 7⏏5}; dd A.new( foo => (1,'string',3) ) expecting any of: constraint |
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| gfldex | A26F64: You can handle such runtime type checks in BUILD or a custom new-method. | 18:49 | |
| A26F64 | m: class A { has Int @.foo }; dd A.new( foo => (1,'string',3) ) | 18:50 | |
| camelia | Type check failed in assignment to @!foo; expected Int but got Str ("string") in block <unit> at <tmp> line 1 |
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| A26F64 | I admit that I often forget about the use of `is` in assignments---as in `my @foo is List`. Though it has been slightly confusing that the various sigils do not uniquely identify a data type. | 18:54 | |
| lizmat | well, @ and % really define roles: Positional and Associative | ||
| A26F64 | But it's wonderful that we have so many types and subtypes. | ||
| And roles. | 18:55 | ||
| lizmat | m: my %b is Bag = <foo bar baz bar foo biz>; dd %b | ||
| camelia | ("foo"=>2,"bar"=>2,"biz"=>1,"baz"=>1).Bag | ||
| A26F64 | For example. | 18:56 | |
| gfldex | The tricky bit is that sigils mean different things depending on where they are used. Raku consists of quite a few sub languages and the doc do a poor job in pointing that out. | ||
| m: constant term:<@container> = 1,2,3; say @container.WHAT; say "@container[]"; | 18:58 | ||
| camelia | (List) 1 2 3 |
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| gfldex | m: constant term:<@container> = 1,2,3; say @container.VAR.WHAT; say "@container[]"; | ||
| camelia | (List) 1 2 3 |
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| gfldex | Quote doesn't care if @container is acutally a container. It just does a scope lookup and the substitution. | 18:59 | |
| m: constant term:<@container> = 'oi‽'; say @container ~~ Positional; say "@container[]"; | 19:01 | ||
| camelia | False oi‽ |
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| A26F64 | But I must say that the documentation is overall excellent. And perhaps I've now learned who is responsible for the plethora of "oi‽"s there? | 19:04 | |
| gfldex | Well spotted. :-> | 19:05 | |
| A26F64 | I want to know what is wrong with my browser every time that I encounter that string. Until I realize that it's another interrobang. | 19:06 | |
| Though I guess that I have become pretty familiar with the documentation pages. | 19:09 | ||
| Well, I am sure that I shall have other questions and may even pose them here. lizmat and gfldex, thank you for your responses and explanations above. I have actually meaning for some time to thank and commend you and other contributors for the weekly news, the documentation, and in general your work on this quite splendid thing. | 19:11 | ||
| lizmat | A26F64 thank you and you're welcome :-) | ||
| Nemokosch | ...so this is what novice questions look like these days 😅 | 19:25 | |
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