CODEWITHSUNDEEP
enumsraku
user1915829
user1915829

Reputation: 619

Constructing enums using Z=> with variables instead of list literals

I would like to construct a String-typed enum. The following works:

my Str enum E ( <a b c> Z=> 'one', 'two', 'three' );
E.kv.raku.say;

("c", "three", "a", "one", "b", "two").Seq

However, trying the following does not:

my Str @a = <a b c>;
my Str @b = <one two three>;
my Str enum F ( @a Z=> @b );
F.kv.raku.say;

No values supplied to enum (does @a Z=> @b need to be declared constant?)

Is this not supported?

Raku/roast covers enum construction like in E but I didn't see any test cases for F.

Out of curiosity, I also tried:

my $a = <a b c>;
my $b = <one two three>;
my Str enum G ( $a<> Z=> $b<>.map( { .Str } ) );
G.kv.raku.say;

("", "").Seq

Upvotes: 9

Views: 147

Answers (2)

jubilatious1
jubilatious1

Reputation: 2341

Can you let us know what Rakudo version? WithRakudo™ v2022.07 and within the Raku REPL, I see virtually identical returns (i.e. no error):

~$ raku
Welcome to Rakudo™ v2022.07.
Implementing the Raku® Programming Language v6.d.
Built on MoarVM version 2022.07.

To exit type 'exit' or '^D'

[0] > my Str enum E ( <a b c> Z=> 'one', 'two', 'three' );
Map.new((a => one, b => two, c => three))
[1] > E.kv.raku.say;
("a", "one", "c", "three", "b", "two").Seq

[1] > my Str @a = <a b c>;
[a b c]
[2] > my Str @b = <one two three>;
[one two three]
[3] > my Str enum F ( @a Z=> @b );
Map.new((a => one, b => two, c => three))
[4] > F.kv.raku.say;
("b", "two", "a", "one", "c", "three").Seq

Upvotes: 1

Jonathan Worthington
Jonathan Worthington

Reputation: 29454

The warning asks:

does @a Z=> @b need to be declared constant

And it's correct; since an enum is a compile-time declaration, everything involved with computing its keys and values must be available at compile time. Declaring @a and @b as constants resolves the problem. Thus:

my constant @a = <a b c>;
my constant @b = <one two three>;
my Str enum F ( @a Z=> @b );
F.kv.raku.say;

Produces:

("a", "one", "c", "three", "b", "two").Seq

Upvotes: 9

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