This channel is intended for people just starting with the Raku Programming Language (raku.org). Logs are available at irclogs.raku.org/raku-beginner/live.html
Set by lizmat on 8 June 2022.
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disbot4 <simon_sibl> I try to understand adverb sub foo(:$bar = False) { say "=> $bar !" } very simple sub when I call it foo:!bar it works but when I do foo:bar it doesnt work with: Undeclared routine: foo:bar am I missing something ? I would like to make a "custom" sub/operator like q which accepts adverb 13:08
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lizmat that's because foo:bar is valid syntax for an identifier 13:18
whereas "foo:!bar" is not, and so that get's interpreted as foo :!bar
it feels like a case of DIHWIDT: just don't say "foo:bar" but "foo :bar" 13:19
disbot4 <simon_sibl> How come q:to works then for example 13:27
lizmat because q: is seen by the grammar as a quoting construct, so it never gets to the "possible identifier" part 13:28
disbot4 <simon_sibl> So it’s not possible to create a similar operator ? Or there is a special way to do it ? 13:29
lizmat is thinking... 13:30
it feels you're getting into slang territory 13:31
and quite deep into that as well
could you give an actual code example you have in mind?
disbot4 <simon_sibl> So I am trying to make a very basic lisp interpreter with “grammar” to train myself And I thought maybe that would be nice to create a “q” like operator which can execute the lisp code with some adverbs modifier 13:32
lizmat an interesting idea :-) 13:33
disbot4 <simon_sibl> I just started learning Raku coming from Perl, it just seems that “everything” is possible in this language xD 13:34
lizmat well... I'd say that's generally true :-)
disbot4 <librasteve> I have been wondering about making a Markdown slang --- but hearing this I realise that something like M/markdown-goes-here/ may work well --- I know I can make that with prefix: <M> or similar --- but most markdown will be longer multiline text so wonders if possible to make some like M:to/END/ for custom heredoc 13:37
lizmat librasteve simon_sibl in RakuAST that may actually be not so complicated, but one would have to get into the grammar and quote language handling 13:38
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disbot4 <librasteve> dang - saly no one has bothered to make a module (like Slangify) for idiots like me 13:39
lizmat I've done a bit in that area, but I would need to re-acquaint myself with that area of the Raku grammar to be able to make sense of that
so please make a Rakudo issue for this, so it doesn't fall through the cracks
disbot4 <librasteve> oh - the voice of an expert ;-) 13:40
<librasteve> I have heard folks moot various low hanging slangs ... markdown, css, json ... to name but three ... but tbh (unless you want syntax highlighting) just a nicer way to grab a source code string and inject into Text::Markdown to return a Str to embed in some web content (of to pass to a LISP compiler) would be just fine 13:43
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disbot4 <simon_sibl> Yeah I’ll first try to make that basic interpreter 😆 Btw silly question, is there an easy way other than “so $var eq any(@array)” or “so @array.grep {$_ eq $var}” to know if an element is in an array ? Later one is more less how I do it in Perl, maybe there is a clever way to do it in Raku ? 13:58
lizmat @array.first(* eq $var) 13:59
disbot4 <simon_sibl> thank you, shorter already ! 14:07
<simon_sibl> similar to the grep one
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disbot4 <nahita3882> $var (elem) @array or $var ∈ @array 14:44
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disbot4 <nahita3882> (elem) and ∈ are aliases to one another; "is element of" operator of set theory 14:46
<nahita3882> but RHS doesn't have to be Setty
<librasteve> dang - if only I'd thought of that!
<nahita3882> to be pedantic, .first is problematic if your $var is Nil because it returns Nil when not found, too 14:47
<nahita3882> (yes your use of eq implies $var is Stringy but still)
<librasteve> yeah - but the idea was to use so xxx and so Nil is False
<nahita3882> but if $var is Nil, and the array does contain Nil, it should give True, no? 14:48
<nahita3882> >>> [Nil,].first(* eqv Nil).so False
<nahita3882> safe way to use first is with its :k adverb and check if the result is strictly Nil (can't do &so because of the result possibly being 0) 14:49
<nahita3882> but why bother when they provide ∈
<librasteve> i prefer ∈ 14:50
<librasteve> fwiw I think that your Nil matches Nil point is debatable - eqv, eq and == are all possible tests depending on what you are working with - and you could make the case that undefined array elems and / or vars should propagate a failure (Nil) 14:55
<nahita3882> i see
<librasteve> (btw I am execting to lose this debate ;-) ) 14:56
<librasteve> m: my @a = 1,2,3, Nil; say Nil ∈ @a 15:07
<Raku eval> False
<librasteve> m: my @a = 1,2,3, Nil; say @a
<Raku eval> [1 2 3 (Any)]
<librasteve> m: my @a = 1,2,3, Nil; say Any ∈ @a
<Raku eval> True
<librasteve> Assigning Nil has the action of resetting the value of a container (ie the element of an Array) to its default and the default is the type object, in this case (Any) 15:09
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disbot4 <librasteve> m: my @a = 1,2,3, Nil; my $x; say $x ∈ @a 15:10
<Raku eval> True
<nahita3882> yeah, though container can be stripped out, e.g., 15:11
<librasteve> I would say that ∈ does pretty much what I would want for a non-tytped piece of code
<nahita3882> m: my @a; @a[0] := Nil; say Nil ∈ @a; say so @a.first(Nil); say @a.first(Nil, :k) !=== Nil; 15:12
<Raku eval> True False True
<librasteve> well there are other Positional types if you want to get fancy, but I prefere (in the beginner) context to use @ sigil and work with Array
<nahita3882> second one is the edge case I was alluding to, which is very-rare-if-ever kind of thing 15:13
<nahita3882> yeah but @a in my snippet is still an Array
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disbot4 <librasteve> true, but you had to do some shenanigans to bypass the container 15:14
<nahita3882> so Arrays having their elements in containers has been a lie?!
<nahita3882> this is some interesting language, especially with this container stuff
<nahita3882> S/interesting/slightly frustrating/ 30% of the time 15:15
<librasteve> lol
<librasteve> strangely consistent 15:16
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SmokeMachine m: say so [1,2,3,Nil].first: { $_ === Nil } 15:44
disbot4 <simon_sibl> just discovered how to type unicode in Emacs, happiest man now 😆 15:45
SmokeMachine Should first return a … but True? 15:48
I mean, if some adverb is passed… 15:53
disbot4 <simon_sibl> m: say 5 ∈ <1 2 3 4 5> 16:02
<Raku eval> False
<simon_sibl> did I miss something ?
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disbot4 <simon_sibl> m: say 5 ∈ (1,2,3,4,5) 16:06
<Raku eval> True
<simon_sibl> okok, the <> was not making Int obviously 16:07
<librasteve> <1 2 3 4 5> means "make me a list of IntStr s"
<librasteve> angle bracket literals are a bit special
<librasteve> <a b c d e> means make me a list of Str s 16:08
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disbot4 <librasteve> m: dd <1/2> 16:08
<simon_sibl> oh IntStr, so it should still work no ? Since IntStr changes depending of context if I got it correctly
<Raku eval> 0.5
<librasteve> and <1/2> is a fraction (aka Rat)
<librasteve> normally you are correct, but Sets use WHICH semantics 16:09
<librasteve> same as '===' operator 16:12
<simon_sibl> m: dd <1/2 3/4 55> 16:13
<Raku eval> (RatStr.new(0.5, "1/2"), RatStr.new(0.75, "3/4"), IntStr.new(55, "55"))
<librasteve> dd is very good to see what you have got
<simon_sibl> m: dd +<1 2 3> 16:15
<Raku eval> 3
<simon_sibl> Hmm
<librasteve> yes well + prefix is same as .elems
<antononcube> Also, deduce-type from "Data::TypeSystem".
<librasteve> (same as in perl iirc)
<simon_sibl> m: say ~$_ for <55 104 4578> 16:17
<Raku eval> 55 104 4578
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disbot4 <simon_sibl> Ah ok with the example I thought it could have translated them to “sentence number” like fifty-five but then would be another issue to choose the language xD 16:18
<librasteve> yeah I can see why ... 16:19
<simon_sibl> “”” my $f = IntStr.new(42, "forty two"); say +$f; # OUTPUT: «42␤» say ~$f; # OUTPUT: «"forty two"␤» “”” 16:20
<librasteve> m: dd <55 104 4578>
<Raku eval> (IntStr.new(55, "55"), IntStr.new(104, "104"), IntStr.new(4578, "4578"))
<librasteve> m: dd <55 104 4578> >> .Str
<Raku eval> Exit code: 1 ===SORRY!=== Error while compiling /home/glot/main.raku Unsupported use of >> to do right shift. In Raku please use: +> or ~>. at /home/glot/main.raku:1 ------> dd <55 104 4578> >>⏏ .Str
<simon_sibl> Oh yeah I need to understand the hyper operators Seem very powerful also 16:21
<simon_sibl> Wait it’s not hyper 16:22
<librasteve> m: { dd $_.Str } for <55 104 4578>
<Raku eval> "55" "104" "4578"
<librasteve> m: { dd $_.Str.WHAT } for <55 104 4578>
<Raku eval> Str Str Str
<simon_sibl> Yeah it’s hyper but there is also the hyper keywords for parallel
<librasteve> yeah >> is short for hyper ... but its often a nice way to map a method over all the elems in a list (as i failed to demonstrate ;-)) 16:23
<simon_sibl> I mean it’s called hyper but there is also the hyper/race no ? 16:24
<librasteve> correct ... it serves both as a handy alternative for map and it schedules the iterations across parallel cores 16:25
<librasteve> m: <a b c d>>>.uc.say 16:26
<Raku eval> (A B C D)
<librasteve> looks a bit weird when you put immediately after another angle bracket 16:27
<antononcube> Use » , then?
<librasteve> m: <a b c d>≫.uc.say 16:28
<Raku eval> Exit code: 1 ===SORRY!=== Error while compiling /home/glot/main.raku Bogus postfix at /home/glot/main.raku:1 ------> <a b c d>⏏≫.uc.say expecting any of: infix infix stopper statement end statement modifier statement modifier loop
<librasteve> good idea 16:29
<simon_sibl> I thought >> and » were the same ? 16:32
<librasteve> me too, I'm stumped on that one 16:33
<librasteve> m: (<a b c d>)>>.uc.say
<Raku eval> (A B C D)
<librasteve> it works with parens to disambiguate, so my guess is that this is a bug in the raku parser 16:34
<librasteve> i'll file an issue
<librasteve> oh - that's a thinko - still filing 16:37
<librasteve> github.com/rakudo/rakudo/issues/5939 16:39
<simon_sibl> m: <<a b c d>>>>.uc.say 16:45
<Raku eval> (A B C D)
<simon_sibl> m: <a b c d> ≫.uc.say
<Raku eval> Exit code: 1 ===SORRY!=== Error while compiling /home/glot/main.raku Confused at /home/glot/main.raku:1 ------> <a b c d>⏏ ≫.uc.say expecting any of: infix infix stopper statement end statement modifier statement modifier loop
<librasteve> But, but ≫ is 226B MUCH GREATER-THAN, not » aka BB RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK ?? 17:34
<librasteve> m: <a b c d> ».uc.say 17:35
<Raku eval> Exit code: 1 ===SORRY!=== Error while compiling /home/glot/main.raku Missing « or » at /home/glot/main.raku:1 ------> <a b c d> ».⏏uc.say
<librasteve> m: <a b c d>».uc.say
<Raku eval> (A B C D)
<librasteve> phew
<librasteve> lizmat: thanks!
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