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 <mimosin...@gmail.com> >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: &P >> > >> > Set.new: K X[,] X.grep: &P >> > >> > 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 <mimosin...@gmail.com> 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 >> -- Joan Pujol Tarrés Departament de Psicologia Social Facultat de Psicologia, Universitat Autònoma de Barcelona Despatx: B5-036 (Passadís Departament Psicologia Social) Edifici B, 08193 Bellaterra (Barcelona), Fax: +34 935812001 http://orcid.org/0000-0002-0462-3278 https://portalrecerca.csuc.cat/orcid/0000-0002-0462-3278
