### Re: list comprehension

Yes, +1 and we have this documented on the py-to-perl6 nutshell page: https://docs.perl6.org/language/py-nutshell#List_comprehensions On Friday, February 22, Lucas Buchala wrote: > Hello folks. Did I understand correctly that this thread is about list > comprehension syntax in Perl 6? :-) > I don't if it was mentioned, but I think this syntax just simply works > already. See an example: > > > say ($_~$_ if $_ %% 2 for ^10).Set > set(00 22 44 66 88) > > > say ($_.item if $_[0] eq 'a' or $_[1] == 2 for X ^3).Set > set((a 0) (a 1) (a 2) (b 2) (c 2)) > > (Just drop the .Set from the end if it's not needed)

### Re: list comprehension

Hello folks. Did I understand correctly that this thread is about list comprehension syntax in Perl 6? :-) I don't if it was mentioned, but I think this syntax just simply works already. See an example: > say ($_~$_ if $_ %% 2 for ^10).Set set(00 22 44 66 88) > say ($_.item if $_[0] eq 'a' or $_[1] == 2 for X ^3).Set set((a 0) (a 1) (a 2) (b 2) (c 2)) (Just drop the .Set from the end if it's not needed)

### Re: list comprehension

El Monday, 11 de February del 2019 a les 17:04, Brad Gilbert va escriure: >Actually I would suggest NOT adding Perl6, because the best way to >create a Set is not to use “list comprehension”, but to just call >`.Set` Ups :O .Thanks for the conceptual clarification. :D I will leave Perl6 out of the wikipedia article. Cheers! >On Mon, Feb 11, 2019 at 12:51 PM mimosinnet >wrote: >> >> Dear Brad, >> >> Thanks very much for the answer. I have been playing with your examples in >> the >> code below (and learned a lot!). Based on your insight, I would suggest these >> solutions to be added to the wikipedia: >> https://en.wikipedia.org/wiki/Set-builder_notation#Parallels_in_programming_languages >> >> Example1: Set.new: gather { for L { take $_ } }; >> Example2: Set.new: cross( K, X.grep: P(x) ); >> >> Cheers! >> >> <--- Working code >> my \L = 1..10; my \K = 1..10; my \X = 5..15; >> >> # Example 1 >> my $e1 = Set.new: gather { for L { take $_ } }; >> >> # Example 2 >> my $s1 = Set.new: gather { >>for K -> \k { >>for X -> \x { >>if x < 8 { >>take (k,x); >>} >>} >>} >> } >> my $s2 = Set.new: (K X[,] X).grep: -> ( \k, \x ) { x < 8 }; >> my $s3 = Set.new: ( -> \x { |(-> \k { (k,x) if x < 8 } for K) } for X ); >> my $s4 = Set.new: gather { -> \k { -> \x { take (k,x) if x < 8; } for X } >> for K } >> my $s5 = Set.new: cross( K, X.grep: * < 8 ); >> >> say $e1; say $s1; say $s2; say $s3; say $s4; say $s5; >> <--- >> >> El Sunday, 10 de February del 2019 a les 12:05, Brad Gilbert va >> escriure: >> >> >In >> > >> > {l for l in L} >> > >> >The reason it is in `{}` is to create a Set from iterating over `L`. >> > >> >> In Python, the set-builder's braces are replaced with square brackets, >> >> parentheses, or curly braces, giving list, generator, and set objects, >> >> respectively. >> > >> >So in Python: >> > >> >[ l for l in L ] gives a list >> >( l for l in L ) gives a generator >> >{ l for l in L } gives a set >> > >> >In Perl6 those would most likely be written as: >> > >> >L.List or L.Array or L.list >> >L.Seq >> >L.Set >> > >> >--- >> > >> >The way to do that is >> > >> >my \L = ((1..10) xx 3).flat.pick(*).list; >> > >> >set( L ) # A >> >L.Set # B >> > >> >my %set is SetHash; >> >{ ++%set{$_} for L } # C >> > >> ># D >> >do { >> ># add the {} syntax to create a Set (lexically) >> >my sub circumfix:«{ }» ( \L ) { L.Set }; >> > >> >{ $_ for L } # <-- >> >} >> > >> >Something that seems similar to me is `unique` >> > >> >.say for L.unique; >> > >> >By that I mean, some places where you would use a Set, it makes sense >> >to use `.unique` instead >> > >> >--- >> > >> >As for `{(k, x) for k in K for x in X if P(x)}` >> > >> >The easiest one to directly translate appears to be the Scala one >> > >> >my \K = 1..10; >> >my \X = 5..15; >> > >> ># for (k <- K; x <- X if P(x)) yield (k,x) >> >Set.new: gather { >> >for K -> \k { >> >for X -> \x { >> >if P(x) { >> >take (k,x); >> >} >> >} >> >} >> >} >> > >> >Other ways: >> > >> >Set.new: (K X[,] X).grep: -> ( \k, \x ) { P(x) } >> > >> >Set.new: K X[,] X.grep: >> > >> >Set.new: K X[,] X.grep: >> > >> >Set.new: ( -> ( \k, \x ) { (k,x) if P(x) } for K X[,] X ) >> > >> >Set.new: ( -> \x { |(-> \k { (k,x) if P x } for K) } for X) >> > >> >On Sun, Feb 10, 2019 at 10:26 AM mimosinnet wrote: >> >> >> >> Hi all, >> >> >> >> I wonder what would be the Perl notation for 'set-builders', as exposed >> >> in this wikipedia article: >> >> >> >> https://en.wikipedia.org/wiki/Set-builder_nota

### Re: list comprehension

Actually I would suggest NOT adding Perl6, because the best way to create a Set is not to use “list comprehension”, but to just call `.Set` That whole page is about Set Builder Notation, but Perl6 doesn't actually have such a thing. You create a Set through a method call, or a subroutine call. That is true even in the translations I did. The closest one is where I added a circumfix operator. my sub circumfix:«{ }» ( \L ) { L.Set }; I mean this: Set.new: gather { for L { take $_ } }; can be simplified to: Set.new( L ); Or if you're being pedantic: Set.new( L.Seq ); On Mon, Feb 11, 2019 at 12:51 PM mimosinnet wrote: > > Dear Brad, > > Thanks very much for the answer. I have been playing with your examples in the > code below (and learned a lot!). Based on your insight, I would suggest these > solutions to be added to the wikipedia: > https://en.wikipedia.org/wiki/Set-builder_notation#Parallels_in_programming_languages > > Example1: Set.new: gather { for L { take $_ } }; > Example2: Set.new: cross( K, X.grep: P(x) ); > > Cheers! > > <--- Working code > my \L = 1..10; my \K = 1..10; my \X = 5..15; > > # Example 1 > my $e1 = Set.new: gather { for L { take $_ } }; > > # Example 2 > my $s1 = Set.new: gather { >for K -> \k { >for X -> \x { >if x < 8 { >take (k,x); >} >} >} > } > my $s2 = Set.new: (K X[,] X).grep: -> ( \k, \x ) { x < 8 }; > my $s3 = Set.new: ( -> \x { |(-> \k { (k,x) if x < 8 } for K) } for X ); > my $s4 = Set.new: gather { -> \k { -> \x { take (k,x) if x < 8; } for X } for > K } > my $s5 = Set.new: cross( K, X.grep: * < 8 ); > > say $e1; say $s1; say $s2; say $s3; say $s4; say $s5; > <--- > > El Sunday, 10 de February del 2019 a les 12:05, Brad Gilbert va > escriure: > > >In > > > > {l for l in L} > > > >The reason it is in `{}` is to create a Set from iterating over `L`. > > > >> In Python, the set-builder's braces are replaced with square brackets, > >> parentheses, or curly braces, giving list, generator, and set objects, > >> respectively. > > > >So in Python: > > > >[ l for l in L ] gives a list > >( l for l in L ) gives a generator > >{ l for l in L } gives a set > > > >In Perl6 those would most likely be written as: > > > >L.List or L.Array or L.list > >L.Seq > >L.Set > > > >--- > > > >The way to do that is > > > >my \L = ((1..10) xx 3).flat.pick(*).list; > > > >set( L ) # A > >L.Set # B > > > >my %set is SetHash; > >{ ++%set{$_} for L } # C > > > ># D > >do { > ># add the {} syntax to create a Set (lexically) > >my sub circumfix:«{ }» ( \L ) { L.Set }; > > > >{ $_ for L } # <-- > >} > > > >Something that seems similar to me is `unique` > > > >.say for L.unique; > > > >By that I mean, some places where you would use a Set, it makes sense > >to use `.unique` instead > > > >--- > > > >As for `{(k, x) for k in K for x in X if P(x)}` > > > >The easiest one to directly translate appears to be the Scala one > > > >my \K = 1..10; > >my \X = 5..15; > > > ># for (k <- K; x <- X if P(x)) yield (k,x) > >Set.new: gather { > >for K -> \k { > >for X -> \x { > >if P(x) { > >take (k,x); > >} > >} > >} > >} > > > >Other ways: > > > >Set.new: (K X[,] X).grep: -> ( \k, \x ) { P(x) } > > > >Set.new: K X[,] X.grep: > > > >Set.new: K X[,] X.grep: > > > >Set.new: ( -> ( \k, \x ) { (k,x) if P(x) } for K X[,] X ) > > > >Set.new: ( -> \x { |(-> \k { (k,x) if P x } for K) } for X) > > > >On Sun, Feb 10, 2019 at 10:26 AM mimosinnet wrote: > >> > >> Hi all, > >> > >> I wonder what would be the Perl notation for 'set-builders', as exposed > >> in this wikipedia article: > >> > >> https://en.wikipedia.org/wiki/Set-builder_notation#Parallels_in_programming_languages > >> > >> This is the Python notation: > >> > >> Example 1: {l for l in L} > >> Example 2: {(k, x) for k in K for x in X if P(x)} > >> > >> This is another example in Python: > >> > >> s = {v for v

### Re: list comprehension

Dear Brad, Thanks very much for the answer. I have been playing with your examples in the code below (and learned a lot!). Based on your insight, I would suggest these solutions to be added to the wikipedia: https://en.wikipedia.org/wiki/Set-builder_notation#Parallels_in_programming_languages Example1: Set.new: gather { for L { take $_ } }; Example2: Set.new: cross( K, X.grep: P(x) ); Cheers! <--- Working code my \L = 1..10; my \K = 1..10; my \X = 5..15; # Example 1 my $e1 = Set.new: gather { for L { take $_ } }; # Example 2 my $s1 = Set.new: gather { for K -> \k { for X -> \x { if x < 8 { take (k,x); } } } } my $s2 = Set.new: (K X[,] X).grep: -> ( \k, \x ) { x < 8 }; my $s3 = Set.new: ( -> \x { |(-> \k { (k,x) if x < 8 } for K) } for X ); my $s4 = Set.new: gather { -> \k { -> \x { take (k,x) if x < 8; } for X } for K } my $s5 = Set.new: cross( K, X.grep: * < 8 ); say $e1; say $s1; say $s2; say $s3; say $s4; say $s5; <--- El Sunday, 10 de February del 2019 a les 12:05, Brad Gilbert va escriure: In {l for l in L} The reason it is in `{}` is to create a Set from iterating over `L`. In Python, the set-builder's braces are replaced with square brackets, parentheses, or curly braces, giving list, generator, and set objects, respectively. So in Python: [ l for l in L ] gives a list ( l for l in L ) gives a generator { l for l in L } gives a set In Perl6 those would most likely be written as: L.List or L.Array or L.list L.Seq L.Set --- The way to do that is my \L = ((1..10) xx 3).flat.pick(*).list; set( L ) # A L.Set # B my %set is SetHash; { ++%set{$_} for L } # C # D do { # add the {} syntax to create a Set (lexically) my sub circumfix:«{ }» ( \L ) { L.Set }; { $_ for L } # <-- } Something that seems similar to me is `unique` .say for L.unique; By that I mean, some places where you would use a Set, it makes sense to use `.unique` instead --- As for `{(k, x) for k in K for x in X if P(x)}` The easiest one to directly translate appears to be the Scala one my \K = 1..10; my \X = 5..15; # for (k <- K; x <- X if P(x)) yield (k,x) Set.new: gather { for K -> \k { for X -> \x { if P(x) { take (k,x); } } } } Other ways: Set.new: (K X[,] X).grep: -> ( \k, \x ) { P(x) } Set.new: K X[,] X.grep: Set.new: K X[,] X.grep: Set.new: ( -> ( \k, \x ) { (k,x) if P(x) } for K X[,] X ) Set.new: ( -> \x { |(-> \k { (k,x) if P x } for K) } for X) On Sun, Feb 10, 2019 at 10:26 AM mimosinnet wrote: Hi all, I wonder what would be the Perl notation for 'set-builders', as exposed in this wikipedia article: https://en.wikipedia.org/wiki/Set-builder_notation#Parallels_in_programming_languages This is the Python notation: Example 1: {l for l in L} Example 2: {(k, x) for k in K for x in X if P(x)} This is another example in Python: s = {v for v in 'ABCDABCD' if v not in 'CB'} https://en.wikipedia.org/wiki/List_comprehension#Similar_constructs I have been playing with the code below. Nevertheless, I am unsure on how to use the code to define a set. Cheers! <--- Code #!/usr/bin/env perl6 my @L = 1 .. 10; my @K = 1 .. 10; my @X = 5 .. 15; say "Example 1:"; for @L -> $l { print "$l " if $l ∈ @L; } say "\nExample 2:"; for @K -> $k { for @X -> $x { print "($k, $x), " if ($k ∈ @K and $x ∈ @X and $x < 8); }} <--- -- (≧∇≦) Mimosinnet (Linux User: #463211) -- (≧∇≦) Mimosinnet (Linux User: #463211) (≧∇≦) Ningún Lugar ★ Activisme Cultural per a la Transformació Social (≧∇≦) Fractalitats en Investigació Crítica * Investigació Crítica per a la Transformació Social * http://psicologiasocial.uab.es/fic

### Re: list comprehension

In {l for l in L} The reason it is in `{}` is to create a Set from iterating over `L`. > In Python, the set-builder's braces are replaced with square brackets, > parentheses, or curly braces, giving list, generator, and set objects, > respectively. So in Python: [ l for l in L ] gives a list ( l for l in L ) gives a generator { l for l in L } gives a set In Perl6 those would most likely be written as: L.List or L.Array or L.list L.Seq L.Set --- The way to do that is my \L = ((1..10) xx 3).flat.pick(*).list; set( L ) # A L.Set # B my %set is SetHash; { ++%set{$_} for L } # C # D do { # add the {} syntax to create a Set (lexically) my sub circumfix:«{ }» ( \L ) { L.Set }; { $_ for L } # <-- } Something that seems similar to me is `unique` .say for L.unique; By that I mean, some places where you would use a Set, it makes sense to use `.unique` instead --- As for `{(k, x) for k in K for x in X if P(x)}` The easiest one to directly translate appears to be the Scala one my \K = 1..10; my \X = 5..15; # for (k <- K; x <- X if P(x)) yield (k,x) Set.new: gather { for K -> \k { for X -> \x { if P(x) { take (k,x); } } } } Other ways: Set.new: (K X[,] X).grep: -> ( \k, \x ) { P(x) } Set.new: K X[,] X.grep: Set.new: K X[,] X.grep: Set.new: ( -> ( \k, \x ) { (k,x) if P(x) } for K X[,] X ) Set.new: ( -> \x { |(-> \k { (k,x) if P x } for K) } for X) On Sun, Feb 10, 2019 at 10:26 AM mimosinnet wrote: > > Hi all, > > I wonder what would be the Perl notation for 'set-builders', as exposed > in this wikipedia article: > > https://en.wikipedia.org/wiki/Set-builder_notation#Parallels_in_programming_languages > > This is the Python notation: > > Example 1: {l for l in L} > Example 2: {(k, x) for k in K for x in X if P(x)} > > This is another example in Python: > > s = {v for v in 'ABCDABCD' if v not in 'CB'} > > https://en.wikipedia.org/wiki/List_comprehension#Similar_constructs > > I have been playing with the code below. Nevertheless, I am unsure on > how to use the code to define a set. > > Cheers! > > <--- Code > #!/usr/bin/env perl6 > > my @L = 1 .. 10; > my @K = 1 .. 10; > my @X = 5 .. 15; > > say "Example 1:"; > for @L -> $l { > print "$l " if $l ∈ @L; > } > > say "\nExample 2:"; > for @K -> $k { for @X -> $x { > print "($k, $x), " if ($k ∈ @K and $x ∈ @X and $x < 8); > }} > <--- > > -- > (≧∇≦) Mimosinnet (Linux User: #463211)

### list comprehension

Hi all, I wonder what would be the Perl notation for 'set-builders', as exposed in this wikipedia article: https://en.wikipedia.org/wiki/Set-builder_notation#Parallels_in_programming_languages This is the Python notation: Example 1: {l for l in L} Example 2: {(k, x) for k in K for x in X if P(x)} This is another example in Python: s = {v for v in 'ABCDABCD' if v not in 'CB'} https://en.wikipedia.org/wiki/List_comprehension#Similar_constructs I have been playing with the code below. Nevertheless, I am unsure on how to use the code to define a set. Cheers! <--- Code #!/usr/bin/env perl6 my @L = 1 .. 10; my @K = 1 .. 10; my @X = 5 .. 15; say "Example 1:"; for @L -> $l { print "$l " if $l ∈ @L; } say "\nExample 2:"; for @K -> $k { for @X -> $x { print "($k, $x), " if ($k ∈ @K and $x ∈ @X and $x < 8); }} <--- -- (≧∇≦) Mimosinnet (Linux User: #463211)