raku

问题 I'm trying to see the way of throwing a map in sink context. In this code class Sunk { has $.titanic; method sink { say "Sinking $!titanic"; } } Sunk.new( :titanic($_) ) for 1..3; (1..3).map: { Sunk.new( :titanic($_) ) }; The for loop effectively sinks all the created, the map does not. Any idea why? This test in roast:https://github.com/perl6/roast/blob/b9bfe1844db25f65a4aeb351a0107f83689cb5c2/S04-statements/sink.t#L27-L32 is supposed to work as a test for that. And map is effectively in a

问题 I'm trying to see the way of throwing a map in sink context. In this code class Sunk { has $.titanic; method sink { say "Sinking $!titanic"; } } Sunk.new( :titanic($_) ) for 1..3; (1..3).map: { Sunk.new( :titanic($_) ) }; The for loop effectively sinks all the created, the map does not. Any idea why? This test in roast:https://github.com/perl6/roast/blob/b9bfe1844db25f65a4aeb351a0107f83689cb5c2/S04-statements/sink.t#L27-L32 is supposed to work as a test for that. And map is effectively in a

问题 ... Or how to change $<sigil>.Str value from token sigil { ... } idependently from the matched text . Yes I'm asking how to cheat grammars above (i.e. calling) me. I am trying to write a Slang for Raku without sigil. So I want the nogil token, matching anything <?> to return NqpMatch that stringifies: $<sigil>.Str to '$'. Currently, my token sigil look like that token sigil { | <[$@%&]> | <nogil> { say "Nogil returned: ", lk($/, 'nogil').Str; # Here It should print "$" } } token nogil-proxy {

问题 FAQ: In Raku how to check if a list is empty ? Are there more idiomatic ways than: my @l = (); say @l.elems == 0; say @l == (); say @l.Bool; The doc on list recommends smartmatching say $l ~~ (); Do you know other ways ? Can you explain why () === () is wrong even if "" === "" is right: I'm not clear on that. 回答1: Of those suggested: say @l.elems == 0; This is a good one to avoid, because it forces evaluation of all elements in a lazy list (which may lead to an exception if there are

问题 FAQ: In Raku, how to check if a String contains a substring ? Where and how many times ? I would like 3 functions such as: xxx-bool("az and az and az again", "az"); # True xxx-num("az and az and az again", "az"); # 3 xxx-list("az and az and az again", "az"); # (0 7 14) PS: Routines index and rindex are pretty cool but only get one match. Related Links: Answer with Regex Answer on List (Array) Contiguous Sequences on List Answer on Hash (Dictionary) 回答1: To check if it contains, use .contains

问题 FAQ: In Raku, how to check if a String contains a substring ? Where and how many times ? I would like 3 functions such as: xxx-bool("az and az and az again", "az"); # True xxx-num("az and az and az again", "az"); # 3 xxx-list("az and az and az again", "az"); # (0 7 14) PS: Routines index and rindex are pretty cool but only get one match. Related Links: Answer with Regex Answer on List (Array) Contiguous Sequences on List Answer on Hash (Dictionary) 回答1: To check if it contains, use .contains

问题 I wrote this test program: await Promise.anyof( Promise.allof((^5).map: {start { sleep 10; say "done $_" } }), Promise.in(5).then: { say 'ouch' } ); sleep 10; When the second promise times out it prints 'ouch' and the await exits, but the first promise's code block is still running. After five more seconds its five processes end and print 'done': $ ./test1.p6 ouch done 0 done 1 done 2 done 3 done 4 I tried to terminate the first promise assigning it to a variable and then calling the .break

问题 To select multiple elements from an array in perl6, it is easy: just use a list of indices: > my @a = < a b c d e f g >; > @a[ 1,3,5 ] (b d f) But to de-select those elements, I had to use Set: > say @a[ (@a.keys.Set (-) (1,3,5)).keys.sort ] (a c e g) I am wondering if there is an easier way because the arrays I use are often quite large? 回答1: sub infix:<not-at> ($elems, @not-ats) { my $at = 0; flat gather for @not-ats -> $not-at { when $at < $not-at { take $at++ xx $not-at - $at } NEXT { $at

问题 Let's say I have a large array, @stuff , and a $thing , and I want to know if $thing is in @stuff . What's the best way to do that in Perl 6? And with “best” I mean: idiomatic, readable, performant; not necessarily in that order. There are actually two separate cases. One is where you have to do a lot of checks for different $thing s, the other is where you only do this once or a few times. Let's look at the first case first. I think I know the (or a) right answer. my $set-of-stuff = set

问题 I try some examples from Rosettacode and encounter an issue with the provided Ackermann example: When running it "unmodified" (I replaced the utf-8 variable names by latin-1 ones), I get (similar, but now copyable): $ perl6 t/ackermann.p6 65533 19729 digits starting with 20035299304068464649790723515602557504478254755697... Cannot unbox 65536 bit wide bigint into native integer in sub A at t/ackermann.p6 line 3 in sub A at t/ackermann.p6 line 11 in sub A at t/ackermann.p6 line 3 in block