On Wed, Feb 12, 2020 at 8:12 AM Aureliano Guedes <guedes.aureli...@gmail.com> wrote:
> > > On Wed, Feb 12, 2020 at 1:09 PM Andy Bach <andy_b...@wiwb.uscourts.gov> > wrote: > >> > So, the problem is you didn't call the same var you had declared. >> >> my $foo = * **2; >> >> > Then you call >> >> foo(2).say >> >> > Missing the $ >> D'oh! Thanks. >> >> > About the >> >> my @a = * **2; >> >> > Your suggestion works >> >> @a[0](2) >> >> > or >> >> @a[0].(2) >> >> > But I would appreciate an explanation about why `$a[0](0)` didn't work. >> >> Same reason as mine didn't work "$a" of "$a[0]" is *not* the same >> variable as @a - raku doesn't swap sigils, so arrays always use @ even when >> they're being dereferenced (?) to a single element - unlike Perl5 >> > Now I see. I din't know that. Thanks. I must study better Raku. > Hi Aureliano, watch about a minute of this Damian Conway video--where he shows the new Raku (Perl6) sigil table: https://youtu.be/Nq2HkAYbG5o?t=568 HTH, Bill. > ------------------------------ >> *From:* Aureliano Guedes <guedes.aureli...@gmail.com> >> *Sent:* Tuesday, February 11, 2020 7:00 PM >> *To:* Andy Bach <andy_b...@wiwb.uscourts.gov>; perl6-users < >> perl6-us...@perl.org> >> *Subject:* Re: variable as subroutine? >> >> Sorry, I sent my answer just for you. >> >> So, the problem is you didn't call the same var you had declared. >> >> my $foo = * **2; >> >> Then you call >> >> foo(2).say >> >> Missing the $ >> Try: >> >> $foo(2).say >> >> or >> >> say $foo(2) >> >> >> About the >> >> my @a = * **2; >> >> Your suggestion works >> >> @a[0](2) >> >> or >> >> @a[0].(2) >> >> But I would appreciate an explanation about why `$a[0](0)` didn't work. >> >> >> On Tue, Feb 11, 2020 at 9:45 PM Andy Bach <andy_b...@wiwb.uscourts.gov> >> wrote: >> >> > I think it should be like this: >> >> > my $foo = * **2; >> { ... } >> > say $foo(4) >> 16 >> >> That's what the doc says, but that's not what my install version says. I >> do get >> > my $foo = * **2; >> { ... } >> >> but say foo get the "unknown sub" error >> >> > But I have another point:: >> >> > my @a = * **2; >> > @a(2) >> Invocant of method 'CALL-ME' must be a type object of type 'List', not an >> object instance of type 'Array'. Did you forget a 'multi'? >> in block <unit> at <unknown file> line 1 >> Yeah, I'd be surprised if that worked >> >> > $a[0](2) >> ===SORRY!=== Error while compiling: >> Variable '$a' is not declared. Did you mean '@a'? >> ------> <BOL>⏏$a[0](2) >> >> raku doesn't swap sigils anymore, so it should be >> @a[0](2) >> >> maybe, pass the param, to the first bucket in @a which is holding a sub, >> so run it - works here >> > my @a = * **2; >> [{ ... }] >> > say @a[0](4); >> 16 >> >> as does ".()" >> > say @a[0].(5); >> 25 >> ------------------------------ >> *From:* Aureliano Guedes <guedes.aureli...@gmail.com> >> *Sent:* Tuesday, February 11, 2020 6:36 PM >> *To:* Andy Bach <andy_b...@wiwb.uscourts.gov> >> *Subject:* Re: variable as subroutine? >> >> I think it should be like this: >> >> > my $foo = * **2; >> { ... } >> > say $foo(4) >> 16 >> >> But I have another point:: >> >> > my @a = * **2; >> [{ ... }] >> > @a(2) >> Invocant of method 'CALL-ME' must be a type object of type 'List', not an >> object instance of type 'Array'. Did you forget a 'multi'? >> in block <unit> at <unknown file> line 1 >> >> > $a[0](2) >> ===SORRY!=== Error while compiling: >> Variable '$a' is not declared. Did you mean '@a'? >> ------> <BOL>⏏$a[0](2) >> >> >> >> On Tue, Feb 11, 2020 at 8:43 PM Andy Bach <andy_b...@wiwb.uscourts.gov> >> wrote: >> >> >The * * * call generates a WhateverCode block. This is expecting 2 >> arguments. >> >> -> $x { $x * $x } is taking one argument. >> >> > The best documentation would probably be : >> https://docs.raku.org/type/Whatever >> >> so, from: >> Multiple * in one expression generate closures with as many arguments: >> >> my $c = * + *; # same as -> $x, $y { $x + $y } >> Using * in complex expressions will also generate closures: >> >> my $c = 4 * * + 5; # same as -> $x { 4 * $x + 5 } >> >> The * * * the parser says "one whatever, one math op (*) and one more >> whatever" >> my $foo = $x, $y { $x + $y }; >> >> so, >> my $foo = * **2; >> should do $x * $x? Though I see >> >> > my $foo = * **2; >> { ... } >> say foo(4); >> ===SORRY!=== Error while compiling: >> Undeclared routine: >> foo used at line 1 >> >> but '&' works >> > my &foo = * **2; >> { ... } >> > foo(4); >> 16 >> > my &c = * **2; >> { ... } >> > say c(4); >> 16 >> >> >> >> >> >> ------------------------------ >> *From:* Simon Proctor <simon.proc...@gmail.com> >> *Sent:* Tuesday, February 11, 2020 9:27 AM >> *To:* Andy Bach <andy_b...@wiwb.uscourts.gov> >> *Cc:* perl6-users <perl6-us...@perl.org> >> *Subject:* Re: variable as subroutine? >> >> The * * * call generates a WhateverCode block. This is expecting 2 >> arguments. >> >> -> $x { $x * $x } is taking one argument. >> >> The best documentation would probably be : >> https://docs.raku.org/type/Whatever >> >> Hope that helps. >> >> (For giggles earlier I made this dumb example of functional programming) >> >> >> my &ident = {$_}; >> my &sq = {$_ * $_}; >> sub trinar( &test, &true, &false, *@values ) { @values.map( -> $v { >> &test($v) ?? &true($v) !! &false($v) } ) }; >> trinar( *.is-prime, &sq,&ident, ^30 ).say >> >> Enjoy. ;) >> >> On Tue, 11 Feb 2020 at 15:22, Andy Bach <andy_b...@wiwb.uscourts.gov> >> wrote: >> >> I have a few less related questions >> >> those are 3 ways to write the same sub: >> >> sub foo ($x) { $x * $x } >> my &foo = -> $x { $x * $x } >> my &foo = * * *; >> >> > A Note on Marc's comment: >> my &foo = * * * >> is not the same as: >> my &foo = -> $x { $x * $x } >> it is the same as: >> my &foo = -> $x, $y { $x * $y } >> >> Okay, "* * *" - how does that work? How is it different than >> -> $x { $x * $x } >> ? It needs two params? >> >> I followed the callable link but that left me with more questions: >> >> method CALL-ME >> method CALL-ME(Callable:D $self: |arguments) >> This method is required for postfix:«( )» and postfix:«.( )». It's what >> makes an object actually call-able and needs to be overloaded to let a >> given object act like a routine. If the object needs to be stored in a >> &-sigiled container, is has to implement Callable. >> >> class A does Callable { >> submethod CALL-ME(|c){ 'called' } >> } >> my &a = A; >> say a(); # OUTPUT: «called» >> >> That second "postfix" operator, means >> say a.(); # also outputs "called" >> >> but what is the "pipe c" signature doing for the submethod? >> ------------------------------ >> *From:* Simon Proctor <simon.proc...@gmail.com> >> *Sent:* Tuesday, February 11, 2020 3:17 AM >> *To:* ToddAndMargo <toddandma...@zoho.com> >> *Cc:* perl6-users <perl6-us...@perl.org> >> *Subject:* Re: variable as subroutine? >> >> If you can store a subroutine in a variable then you can pass said >> subroutine to another one as an argument. >> >> This leads us into the joys of functional programming. >> >> And you may have used it already and not even realised. >> >> The .map and .grep methods (and .reduce and bunch of others) all expect a >> callable code block (that might be a subroutine) as a function. >> >> This : >> >> my @a = (1..10).map( * ** 2 ) >> >> and this : >> >> my &sq = sub ($v) { $v ** 2 }; >> my @a = (1..10).map( &sq ); >> >> are doing the same thing. Except the second one has the &sq function >> available for other things. >> >> (A Note on Marc's comment * * * is not the same as -> $x { $x * $x } it >> is the same as -> $x, $y { $x * $y } ) >> >> You can then start doing things like storing functions as values in >> hashes and doing all *kinds* of fun stuff. >> >> Welcome to the tip of the iceberg. >> >> Simon >> >> >> On Tue, 11 Feb 2020 at 03:21, ToddAndMargo via perl6-users < >> perl6-us...@perl.org> wrote: >> >> Hi All, >> >> Is Larry using his magic powder again? >> >> Can I declare a subroutine as a variable? >> >> my $abc = my sub (UInt $u, Str $s, Int $I) { >> >> How would I use it? >> >> And why would do such a thing? >> >> -T >> >> >> >> -- >> Simon Proctor >> Cognoscite aliquid novum cotidie >> >> http://www.khanate.co.uk/ >> >> >> >> -- >> Simon Proctor >> Cognoscite aliquid novum cotidie >> >> http://www.khanate.co.uk/ >> >> >> >> -- >> Aureliano Guedes >> skype: aureliano.guedes >> contato: (11) 94292-6110 >> whatsapp +5511942926110 >> >> >> >> -- >> Aureliano Guedes >> skype: aureliano.guedes >> contact: (11) 94292-6110 >> WhatsApp +5511942926110 >> > > > -- > Aureliano Guedes > skype: aureliano.guedes > contato: (11) 94292-6110 > whatsapp +5511942926110 >
