A selection of 101 LINQ Samples converted to Rust

gistfile1.txt

// Port of the C# 101 LINQ Samples rewritten into Apple's Swift 3.

#![feature(ordering_chaining, step_by)]

fn main() {
    // linq5: Where - Indexed
    /*
    //c#
    public void Linq5()
    {
        string[] digits = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };

        var shortDigits = digits.Where((digit, index) => digit.Length < index);

        Console.WriteLine("Short digits:");
        foreach (var d in shortDigits)
        {
            Console.WriteLine("The word {0} is shorter than its value.", d);
        }
    }

    //swift
    func linq5(){
        let digits = ["zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"]

        let shortDigits = digits.filteri { $0.length < $1 }

        print("Short digits:")
        for d in shortDigits {
            print("The word \(d) is shorter than its value.")
        }
    }
    */

    // Rust
    {
        let digits = ["zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"];
        let short_digits = digits
                           .iter()
                           .enumerate()
                           .filter(|&(index, &digit)| digit.len() < index)
                           .map(|(_, &digit)| digit);

        println!("Short digits:");
        for d in short_digits {
            println!("The word {} is shorter than its value.", d);
        }
    }

    //-------------------------------------------------------

    // linq9: Select - Anonymous Types 1
    /*
    //c#
    public void Linq9()
    {
        string[] words = { "aPPLE", "BlUeBeRrY", "cHeRry" };

        var upperLowerWords =
            from w in words
            select new { Upper = w.ToUpper(), Lower = w.ToLower() };

        foreach (var ul in upperLowerWords)
        {
            Console.WriteLine("Uppercase: {0}, Lowercase: {1}", ul.Upper, ul.Lower);
        }
    }

    //swift
    func linq9(){
        let words = ["aPPLE", "BlUeBeRrY", "cHeRry"]

        let upperLowerWords = words.map { s -> (Upper: String, Lower:String) in
            (s.uppercased(), s.lowercased())
        }

        for ul in upperLowerWords {
            print("Uppercase: \(ul.Upper), Lowercase: \(ul.Lower)")
        }
    }
    */

    // Rust
    {
        let words = ["aPPLE", "BlUeBeRrY", "cHeRry"];

        struct ULPair { upper: String, lower: String }
        let upper_lower_words =
            words
            .iter()
            .map(|&w| ULPair {upper: w.to_uppercase(), lower: w.to_lowercase()});

        for ul in upper_lower_words {
            println!("Uppercase: {}, Lowercase: {}", ul.upper, ul.lower);
        }
    }

    //-------------------------------------------------------

    // linq14: SelectMany - Compound from 1
    /*
    //c#
    public void Linq14()
    {
        int[] numbersA = { 0, 2, 4, 5, 6, 8, 9 };
        int[] numbersB = { 1, 3, 5, 7, 8 };

        var pairs =
            from a in numbersA
            from b in numbersB
            where a < b
            select new { a, b };

        Console.WriteLine("Pairs where a < b:");
        foreach (var pair in pairs)
        {
            Console.WriteLine("{0} is less than {1}", pair.a, pair.b);
        }
    }

    //swift
    func linq14(){
        let numbersA = [ 0, 2, 4, 5, 6, 8, 9 ]
        let numbersB = [ 1, 3, 5, 7, 8 ]

        let pairs = numbersA.expand { a in
            numbersB
                .filter { b in a < b }
                .map { i -> (a: Int, b:Int) in (a, i) }
            }

        print("Pairs where a < b:")
        for pair in pairs {
            print("\(pair.a) is less than \(pair.b)")
        }
    }
    */

    // Rust
    {
        let numbers_a = [0, 2, 4, 5, 6, 8, 9];
        let numbers_b = [1, 3, 5, 7, 8];

        let pairs = numbers_a
                    .iter()
                    .flat_map(|&a| numbers_b
                                   .iter()
                                   .filter(move |&&b| a < b)
                                   .map(move |&b| (a, b)));

        println!("Pairs where a < b:");
        for (a, b) in pairs {
            println!("{} is less than {}", a, b);
        }
    }

    //-------------------------------------------------------

    // linq25: TakeWhile - Indexed
    /*
    //c#
    public void Linq25()
    {
        int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };

        var firstSmallNumbers = numbers.TakeWhile((n, index) => n >= index);

        Console.WriteLine("First numbers not less than their position:");
        foreach (var n in firstSmallNumbers)
        {
            Console.WriteLine(n);
        }
    }

    //swift
    func linq25(){
        let numbers = [ 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 ]

        var index = 0
        let firstSmallNumbers = numbers.takeWhile { index += 1; return $0 >= index }

        print("First numbers not less than their position:")
        firstSmallNumbers.forEach { print($0) }
    }
    */

    // Rust
    {
        let numbers = [5, 4, 1, 3, 9, 8, 6, 7, 2, 0];

        let first_small_numbers = numbers
                                  .iter()
                                  .enumerate()
                                  .take_while(|&(index, &n)| n >= index)
                                  .map(|(_, &n)| n);

        println!("First numbers not less than their position:");
        for n in first_small_numbers {
            println!("{}", n);
        }
    }

    //-------------------------------------------------------
    // linq27: SkipWhile - Indexed
    /*
    //c#
    public void Linq27()
    {
        int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };

        var laterNumbers = numbers.SkipWhile((n, index) => n >= index);

        Console.WriteLine("All elements starting from first element less than its position:");
        foreach (var n in laterNumbers)
        {
            Console.WriteLine(n);
        }
    }

    //swift
    func linq27(){
        let numbers = [ 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 ]

        var index = 0
        let laterNumbers = numbers.skipWhile { index += 1; return $0 >= index }

        print("All elements starting from first element less than its position:")
        laterNumbers.forEach { print($0) }
    }
    */

    // Rust
    {
        let numbers = [5, 4, 1, 3, 9, 8, 6, 7, 2, 0];

        let later_numbers = numbers
                            .iter()
                            .enumerate()
                            .skip_while(|&(index, &n)| n >= index)
                            .map(|(_, &n)| n);

        println!("All elements starting from first element less than its position:");
        for n in later_numbers {
            println!("{}", n);
        }
    }

    //-------------------------------------------------------

    // linq31: OrderBy - Comparer
    /*
    //c#
    public void Linq31()
    {
        string[] words = { "aPPLE", "AbAcUs", "bRaNcH", "BlUeBeRrY", "ClOvEr", "cHeRry" };

        var sortedWords = words.OrderBy(a => a, new CaseInsensitiveComparer());

        ObjectDumper.Write(sortedWords);
    }

    //swift
    func linq31(){
        let words = [ "aPPLE", "AbAcUs", "bRaNcH", "BlUeBeRrY", "ClOvEr", "cHeRry" ]

        let sortedWords = words.sorted(by: caseInsensitiveComparer)

        sortedWords.forEach { print($0) }
    }
    */

    // Rust
    {
        let words = ["aPPLE", "AbAcUs", "bRaNcH", "BlUeBeRrY", "ClOvEr", "cHeRry"];

        let mut sorted_words = words.to_vec();
        sorted_words.sort_by_key(|&w| w.to_lowercase());

        println!("{:?}", sorted_words);
    }

    //-------------------------------------------------------
    // linq32: OrderByDescending - Simple 1
    /*
    //c#
    public void Linq32()
    {
        double[] doubles = { 1.7, 2.3, 1.9, 4.1, 2.9 };

        var sortedDoubles =
            from d in doubles
            orderby d descending
            select d;

        Console.WriteLine("The doubles from highest to lowest:");
        foreach (var d in sortedDoubles)
        {
            Console.WriteLine(d);
        }
    }

    //swift
    func linq32(){
        let doubles = [ 1.7, 2.3, 1.9, 4.1, 2.9 ]

        let sortedDoubles = doubles.sorted().reversed()

        print("The doubles from highest to lowest:")
        sortedDoubles.forEach { print($0) }
    }
    */

    // Rust
    {
        let doubles = [1.7, 2.3, 1.9, 4.1, 2.9];

        use std::cmp::Ordering::*;
        let mut sorted_doubles = doubles.to_vec();
        //sorted_doubles.sort_by(|a, b| b.partial_cmp(a).unwrap());
        sorted_doubles.sort_by(|a, b| if a < b {Greater} else if a > b {Less} else {Equal});

        println!("The doubles from highest to lowest:");
        println!("{:?}", sorted_doubles);
    }

    //-------------------------------------------------------
    // linq35: ThenBy - Simple

    /*
    //c#
    public void Linq35()
    {
        string[] digits = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };

        var sortedDigits =
            from d in digits
            orderby d.Length, d
            select d;

        Console.WriteLine("Sorted digits:");
        foreach (var d in sortedDigits)
        {
            Console.WriteLine(d);
        }
    }

    //swift
    func linq35(){
        let digits = [ "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" ]

        let sortedDigits = digits.sorted { $0 < $1 }.sorted { $0.length < $1.length }

        print("Sorted digits:")
        sortedDigits.forEach { print($0) }
    }
    */

    // Rust
    {
        let digits = ["zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"];

        let mut sorted_digits = digits.to_vec();
        sorted_digits.sort_by_key(|&w| (w.len(), w));

        // Alternative solution 1:
        // sorted_digits.sort_by(|a, b| a.len().cmp(&b.len()).then(a.cmp(b)));

        // Alternative solution 2:
        // sorted_digits.sort_by(|a, b| a.len().cmp(&b.len()).then_with(|| a.cmp(b)));

        println!("Sorted digits:");
        println!("{:?}", sorted_digits);
    }

    //-------------------------------------------------------

    // linq38: ThenByDescending - Comparer

    /*
    //c#
    public void Linq38()
    {
        string[] words = { "aPPLE", "AbAcUs", "bRaNcH", "BlUeBeRrY", "ClOvEr", "cHeRry" };

        var sortedWords =
            words.OrderBy(a => a.Length)
                 .ThenByDescending(a => a, new CaseInsensitiveComparer());

        ObjectDumper.Write(sortedWords);
    }

    //swift
    func linq38(){
        let words = [ "aPPLE", "AbAcUs", "bRaNcH", "BlUeBeRrY", "ClOvEr", "cHeRry" ]

        let sortedWords = words.sortBy(
            { compare($0.length,$1.length) },
            { compareIgnoreCase($1,$0) }
        )

        sortedWords.forEach { print($0) }
    }
    */

    // Rust
    {
        let words = ["aPPLE", "AbAcUs", "bRaNcH", "BlUeBeRrY", "ClOvEr", "cHeRry"];

        let mut sorted_words = words.to_vec();

        sorted_words.sort_by(|a, b| a.len().cmp(&b.len())
                                    .then_with(|| b.to_lowercase().cmp(&a.to_lowercase())));

        println!("{:?}", sorted_words);
    }

    //-------------------------------------------------------
    // linq39: Reverse
    /*
    //c#
    public void Linq39()
    {
        string[] digits = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" };

        var reversedIDigits = (
            from d in digits
            where d[1] == 'i'
            select d)
            .Reverse();

        Console.WriteLine("A backwards list of the digits with a second character of 'i':");
        foreach (var d in reversedIDigits)
        {
            Console.WriteLine(d);
        }
    }

    //swift
    func linq39(){
        let digits = [ "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine" ]

        let reversedIDigits = digits
            .filter { $0.charAt(1) == "i" }
            .reversed()

        print("A backwards list of the digits with a second character of 'i':")
        reversedIDigits.forEach { print($0) }
    }
    */

    // Rust
    {
        let digits = ["zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"];

        let reversed_i_digits = digits
                                .iter()
                                .filter(|&w| w.chars().nth(1).unwrap() == 'i')
                                .rev();

        println!("A backwards list of the digits with a second character of 'i':");
        for d in reversed_i_digits {
            println!("{}", d);
        }
    }

    //-------------------------------------------------------
    // linq40: GroupBy - Simple 1
    /*
    //c#
    public void Linq40()
    {
        int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };

        var numberGroups =
            from n in numbers
            group n by n % 5 into g
            select new { Remainder = g.Key, Numbers = g };

        foreach (var g in numberGroups)
        {
            Console.WriteLine("Numbers with a remainder of {0} when divided by 5:", g.Remainder);
            foreach (var n in g.Numbers)
            {
                Console.WriteLine(n);
            }
        }
    }

    //swift
    func linq40(){
        let numbers = [ 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 ]

        let numberGroups = numbers.groupBy { $0 % 5 }
            .map { g -> (Remainder: Int, Numbers: Group<Int,Int>) in
                (g.key, g)
            }

        for g in numberGroups {
            print("Numbers with a remainder of \(g.Remainder) when divided by 5:")
            g.Numbers.items.forEach { print($0) }
        }
    }
    */

    // Rust
    {
        let numbers = [5, 4, 1, 3, 9, 8, 6, 7, 2, 0];

        use std::collections::HashMap;
        let mut number_groups = HashMap::new();
        for &n in &numbers {
            number_groups.entry(n % 5).or_insert(vec![]).push(n);
        }

        for (m, group) in number_groups.iter() {
            println!("Numbers with a remainder of {} when divided by 5:", m);
            println!("{:?}", group);
        }
    }

    //-------------------------------------------------------

    // linq44: GroupBy - Comparer
    /*
    //c#
    public void Linq44()
    {
        string[] anagrams = { "from   ", " salt", " earn ", "  last   ", " near ", " form  " };

        var orderGroups = anagrams.GroupBy(w => w.Trim(), new AnagramEqualityComparer());

        ObjectDumper.Write(orderGroups, 1);
    }

    //swift
    func linq44(){
        let anagrams = [ "from   ", " salt", " earn ", "  last   ", " near ", " form  " ]

        let orderGroups = anagrams.groupBy({ (s:String) in s.trim() }, matchWith: anagramComparer)

        orderGroups.forEach { print($0.items) }
    }
    */

    // Rust
    {
        let words = ["from   ", " salt", " earn ", "  last   ", " near ", " form  "];

        use std::collections::HashMap;
        let mut anagram_groups = HashMap::new();
        for &w in &words {
            let mut key = w.trim().chars().collect::<Vec<_>>();
            key.sort();
            anagram_groups.entry(key).or_insert(vec![]).push(w);
        }

        for group in anagram_groups.values() {
            println!("{:?}", group);
        }
    }
    //-------------------------------------------------------

    // linq46: Distinct - 1
    /*
    //c#
    public void Linq46()
    {
        int[] factorsOf300 = { 2, 2, 3, 5, 5 };

        var uniqueFactors = factorsOf300.Distinct();

        Console.WriteLine("Prime factors of 300:");
        foreach (var f in uniqueFactors)
        {
            Console.WriteLine(f);
        }
    }

    //swift
    func linq46(){
        let factorsOf300 = [ 2, 2, 3, 5, 5 ]

        let uniqueFactors = distinct(factorsOf300)

        print("Prime factors of 300:")
        uniqueFactors.forEach { print($0) }
    }
    */

    // Rust
    {
        let factors_of_300 = [2, 2, 3, 5, 5];

        let mut unique_factors = factors_of_300.to_vec();
        unique_factors.dedup();

        println!("Prime factors of 300:");
        println!("{:?}", unique_factors);

        // Alternative solution 1:
        use std::collections::HashSet;
        let unique_factors = factors_of_300.iter().cloned().collect::<HashSet<_>>();

        println!("Prime factors of 300:");
        for f in unique_factors {
            println!("{}", f);
        }

        // Alternative solution 2:
        // https://docs.rs/itertools/0.5.9/itertools/trait.Itertools.html#method.dedup
    }

    //-------------------------------------------------------
    // linq48: Union - 1

    /*
    //c#
    public void Linq48()
    {
        int[] numbersA = { 0, 2, 4, 5, 6, 8, 9 };
        int[] numbersB = { 1, 3, 5, 7, 8 };

        var uniqueNumbers = numbersA.Union(numbersB);

        Console.WriteLine("Unique numbers from both arrays:");
        foreach (var n in uniqueNumbers)
        {
            Console.WriteLine(n);
        }
    }

    //swift
    func linq48(){
        let numbersA = [ 0, 2, 4, 5, 6, 8, 9 ]
        let numbersB = [ 1, 3, 5, 7, 8 ]

        let uniqueNumbers = union(numbersA, numbersB)

        print("Unique numbers from both arrays:")
        uniqueNumbers.forEach { print($0) }
    }

    Output

    Unique numbers from both arrays:
    0
    2
    4
    5
    6
    8
    9
    1
    3
    7
    */

    // Rust
    {
        let numbers_a = [0, 2, 4, 5, 6, 8, 9];
        let numbers_b = [1, 3, 5, 7, 8];

        use std::collections::HashSet;
        let sa = &numbers_a.iter().cloned().collect::<HashSet<u32>>();
        let sb = &numbers_b.iter().cloned().collect::<HashSet<u32>>();
        let unique_numbers = sa.union(&sb);

        println!("Unique numbers from both arrays:");
        for n in unique_numbers {
            println!("{}", n);
        }
    }

    //-------------------------------------------------------
    // linq50: Intersect - 1
    /*
    //c#
    public void Linq50()
    {
        int[] numbersA = { 0, 2, 4, 5, 6, 8, 9 };
        int[] numbersB = { 1, 3, 5, 7, 8 };

        var commonNumbers = numbersA.Intersect(numbersB);

        Console.WriteLine("Common numbers shared by both arrays:");
        foreach (var n in commonNumbers)
        {
            Console.WriteLine(n);
        }
    }

    //swift
    func linq50(){
        let numbersA = [ 0, 2, 4, 5, 6, 8, 9 ]
        let numbersB = [ 1, 3, 5, 7, 8 ]

        let commonNumbers = intersection(numbersA, numbersB)

        print("Common numbers shared by both arrays:")
        commonNumbers.forEach { print($0) }
    }
    */

    // Rust
    {
        let numbers_a = [0, 2, 4, 5, 6, 8, 9];
        let numbers_b = [1, 3, 5, 7, 8];

        use std::collections::HashSet;
        let sa = &numbers_a.iter().cloned().collect::<HashSet<u32>>();
        let sb = &numbers_b.iter().cloned().collect::<HashSet<u32>>();
        let common_numbers = sa.intersection(&sb);

        println!("Common numbers shared by both arrays:");
        for n in common_numbers {
            println!("{}", n);
        }
    }

    //-------------------------------------------------------
    // linq52: Except - 1
    /*
    //c#
    public void Linq52()
    {
        int[] numbersA = { 0, 2, 4, 5, 6, 8, 9 };
        int[] numbersB = { 1, 3, 5, 7, 8 };

        IEnumerable<int> aOnlyNumbers = numbersA.Except(numbersB);

        Console.WriteLine("Numbers in first array but not second array:");
        foreach (var n in aOnlyNumbers)
        {
            Console.WriteLine(n);
        }
    }

    //swift
    func linq52(){
        let numbersA = [ 0, 2, 4, 5, 6, 8, 9 ]
        let numbersB = [ 1, 3, 5, 7, 8 ]

        let aOnlyNumbers = difference(numbersA, other: numbersB)

        print("Numbers in first array but not second array:")
        aOnlyNumbers.forEach { print($0) }
    }
    */

    // Rust
    {
        let numbers_a = [0, 2, 4, 5, 6, 8, 9];
        let numbers_b = [1, 3, 5, 7, 8];

        use std::collections::HashSet;
        let sa = &numbers_a.iter().cloned().collect::<HashSet<u32>>();
        let sb = &numbers_b.iter().cloned().collect::<HashSet<u32>>();
        let common_numbers = sa.difference(&sb);

        println!("Numbers in first array but not second array:");
        for n in common_numbers {
            println!("{}", n);
        }
    }

    //-------------------------------------------------------
    // linq54: ToArray
    /*
    //c#
    public void Linq54()
    {
        double[] doubles = { 1.7, 2.3, 1.9, 4.1, 2.9 };

        var sortedDoubles =
            from d in doubles
            orderby d descending
            select d;
        var doublesArray = sortedDoubles.ToArray();

        Console.WriteLine("Every other double from highest to lowest:");
        for (int d = 0; d < doublesArray.Length; d += 2)
        {
            Console.WriteLine(doublesArray[d]);
        }
    }

    //swift
    func linq54(){
        let doubles = [ 1.7, 2.3, 1.9, 4.1, 2.9 ]

        let sortedDoubles = doubles.sorted().reversed()

        let doublesArray = sortedDoubles.toArray()

        print("Every other double from highest to lowest:")
        var d = 0
        while d < doublesArray.count {
            print(doublesArray[d])
            d += 2
        }
    }
    */

    // Rust
    {
        let mut doubles = [1.7, 2.3, 1.9, 4.1, 2.9];

        use std::cmp::Ordering::*;
        doubles.sort_by(|a, b| if a < b {Greater} else if a > b {Less} else {Equal});
        let doubles_vector = doubles.to_vec();

        println!("Every other double from highest to lowest:");
        for i in (0 .. doubles_vector.len()).step_by(2) {
            println!("{}", doubles_vector[i]);
        }
    }

    //-------------------------------------------------------
    // linq56: ToDictionary
    /*
    //c#
    public void Linq56()
    {
        var scoreRecords = new[] { new {Name = "Alice", Score = 50},
                                    new {Name = "Bob"  , Score = 40},
                                    new {Name = "Cathy", Score = 45}
                                };

        var scoreRecordsDict = scoreRecords.ToDictionary(sr => sr.Name);

        Console.WriteLine("Bob's score: {0}", scoreRecordsDict["Bob"]);
    }

    //swift
    func linq56(){
        let scoreRecords = [
            ( Name: "Alice", Score: 50),
            ( Name: "Bob", Score: 40),
            ( Name: "Cathy", Score: 45),
        ]

        let scoreRecordsDict = scoreRecords.toDictionary {
            (x:(Name:String,Score:Int)) in x.Name
        }

        let bobsScore = scoreRecordsDict["Bob"]!
        print("Bob's score: \(bobsScore)")
    }
    */

    // Rust
    {
        let score_tuples = [("Alice", 50), ("Bob", 40), ("Cathy", 45)];

        use std::collections::HashMap;
        let score_dict: HashMap<_,_> = score_tuples.iter().cloned().collect();

        println!("Bob's score: {}", score_dict["Bob"]);
    }

    //-------------------------------------------------------
    // linq61: FirstOrDefault - Simple
    /*
    //c#
    public void Linq61()
    {
        int[] numbers = { };

        int firstNumOrDefault = numbers.FirstOrDefault();

        Console.WriteLine(firstNumOrDefault);
    }

    //swift
    func linq61(){
        let numbers:[Int] = []

        let firstNumOrDefault = numbers.firstWhere({ n in true }, orElse: { 0 })

        print(firstNumOrDefault)
    }
    */

    // Rust
    {
        let numbers: [u32; 0] = [];
        let zero = 0;
        let first_num_or_default = numbers.get(0).unwrap_or(&zero);

        println!("{}", first_num_or_default);
    }

    //-------------------------------------------------------
    // linq73: Count - Simple
    /*
    //c#
    public void Linq73()
    {
        int[] factorsOf300 = { 2, 2, 3, 5, 5 };

        int uniqueFactors = factorsOf300.Distinct().Count();

        Console.WriteLine("There are {0} unique factors of 300.", uniqueFactors);
    }

    //swift
    func linq73(){
        let factorsOf300 = [ 2, 2, 3, 5, 5 ]

        let uniqueFactors = distinct(factorsOf300).count

        print("There are \(uniqueFactors) unique factors of 300.")
    }
    */

    // Rust
    {
        let factors_of_300 = [2, 2, 3, 5, 5];

        use std::collections::HashSet;
        let unique_factors = factors_of_300
                             .iter()
                             .cloned()
                             .collect::<HashSet<_>>()
                             .len();

        println!("There are {} unique factors of 300.", unique_factors);
    }
    //-------------------------------------------------------

    // linq88: Max - Elements
    /*
    //c#
    public void Linq88()
    {
        List<Product> products = GetProductList();

        var categories =
            from p in products
            group p by p.Category into g
            let maxPrice = g.Max(p => p.UnitPrice)
            select new { Category = g.Key, MostExpensiveProducts = g.Where(p => p.UnitPrice == maxPrice) };

        ObjectDumper.Write(categories, 1);
    }

    //swift
    func linq88(){
        let products = productsList()

        let categories = products.groupBy { (p:Product) in p.category }
            .map { g -> (Category:String, MostExpensiveProducts:[Product]) in
                let maxPrice:Double = g.items.maxElement { (p:Product) in p.unitPrice }
                return (g.key, g.items.filter { $0.unitPrice == maxPrice })
        }

        categories.forEach {
            print("\($0.Category): ")
            $0.MostExpensiveProducts.forEach { print($0) }
        }
    }
    */

    // Rust
    {
        let products = [(5, 2), (1, 4), (3, 1), (7, 4)];

        let max_price = products.iter().map(|&(_, b)| b).max().unwrap();
        let result = products.iter().filter(|&&(_, b)| b == max_price);

        println!("Max pairs:");
        for pair in result {
            println!("{:?}", pair);
        }
    }

    //-------------------------------------------------------
    // linq90: Average - Projection
    /*
    //c#
    public void Linq90()
    {
        string[] words = { "cherry", "apple", "blueberry" };

        double averageLength = words.Average(w => w.Length);

        Console.WriteLine("The average word length is {0} characters.", averageLength);
    }

    //swift
    func linq90(){
        let words = [ "cherry", "apple", "blueberry" ]

        let averageLength = words.map { $0.length }.avg { $0 as Int }

        print("The average word length is \(averageLength) characters.")
    }
    */

    // Rust
    {
        let words = ["cherry", "apple", "blueberry"];

        let average_len: usize = words.iter().map(|w| w.chars().count()).sum();

        println!("The average word length is {} characters.",
                 average_len as f64 / words.len() as f64);
    }

    //-------------------------------------------------------
    // linq94: Concat - 1
    /*
    //c#
    public void Linq94()
    {
        int[] numbersA = { 0, 2, 4, 5, 6, 8, 9 };
        int[] numbersB = { 1, 3, 5, 7, 8 };

        var allNumbers = numbersA.Concat(numbersB);

        Console.WriteLine("All numbers from both arrays:");
        foreach (var n in allNumbers)
        {
            Console.WriteLine(n);
        }
    }

    //swift
    func linq94(){
        let numbersA = [ 0, 2, 4, 5, 6, 8, 9 ]
        let numbersB = [ 1, 3, 5, 7, 8 ]

        let allNumbers = numbersA + numbersB

        print("All numbers from both arrays:")
        allNumbers.forEach { print($0) }
    }
    */

    // Rust
    {
        let numbers_a = [0, 2, 4, 5, 6, 8, 9];
        let numbers_b = [1, 3, 5, 7, 8];

        let all_numbers = [&numbers_a[..], &numbers_b[..]].concat();

        println!("All numbers from both arrays:");
        println!("{:?}", all_numbers);

        // Alternative version:
        for el in numbers_a.iter().chain(&numbers_b) {
            println!("{}", el);
        }
    }

    //-------------------------------------------------------
    // linq96: EqualAll - 1
    /*
    //c#
    public void Linq96()
    {
        var wordsA = new string[] { "cherry", "apple", "blueberry" };
        var wordsB = new string[] { "cherry", "apple", "blueberry" };

        bool match = wordsA.SequenceEqual(wordsB);

        Console.WriteLine("The sequences match: {0}", match);
    }

    //swift
    func linq96(){
        let wordsA = [ "cherry", "apple", "blueberry" ]
        let wordsB = [ "cherry", "apple", "blueberry" ]

        let match = wordsA == wordsB

        print("The sequences match: \(match)")
    }
    */

    // Rust
    {
        let words_a = ["cherry", "apple", "blueberry"];
        let words_b = ["cherry", "apple", "blueberry"];

        let equal_words = words_a == words_b;
        println!("The sequences match: {}", equal_words);

        // Alternative solution:
        let equal_words2 = words_a.iter().eq(&words_b);
        println!("The sequences match: {}", equal_words2);
    }

    //-------------------------------------------------------
}

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