functional programming - What is the raku equivalent of the JavaScript arrow function? - Stack Overflow

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In JavaScript, I can go

const materials = [
  'Hydrogen',
  'Helium',
  'Lithium',
  'Beryllium'
];

console.log(materials.map(material => material.length));
// expected output: Array [8, 6, 7, 9]

I guess that raku has some chops in functional - and I wonder if someone can clarify the equivalent code (see )

In JavaScript, I can go

const materials = [
  'Hydrogen',
  'Helium',
  'Lithium',
  'Beryllium'
];

console.log(materials.map(material => material.length));
// expected output: Array [8, 6, 7, 9]

I guess that raku has some chops in functional - and I wonder if someone can clarify the equivalent code (see https://developer.mozilla/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions )

• javascript
• functional-programming
• raku

Share Improve this question Follow edited Jul 7, 2020 at 12:47 raiph 32.5k33 gold badges6464 silver badges111111 bronze badges asked Jul 6, 2020 at 20:22 librastevelibrasteve 7,6211010 silver badges3333 bronze badges 2

• What feature of arrow functions are you looking to replicate? Lexical this binding? Short-hand syntax where the body of the function is an expression rather than a block? The ability to create a function using the => symbols? – Quentin Commented Jul 6, 2020 at 20:26
• hi @quentin - the latter i.e. ability to create a function with => – librasteve Commented Jul 6, 2020 at 21:08

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Sorted by: Reset to default 18

The most direct equivalent would be

my @materials = <Hydrogen Helium Lithium Beryllium>;
say @materials.map(-> $material { $material.chars });

but an arrow sub is more explicit than you need in this case, because

say @materials.map: *.chars;

would also be sufficient (method call on a "whatever star" returns a code block that calls that method on its argument), and

say @materials».chars;

would also work (hyper-application applied to the dot operator).

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