I'm working on modernizing Rosetta Code's infrastructure. Starting with communications. Please accept this time-limited open invite to RC's Slack.. --Michael Mol (talk) 20:59, 30 May 2020 (UTC)

# Category talk:Wren-rat

### Source code

`/* Module "rat.wren" */ import "./trait" for Comparable /* Rat represents a rational number as an integral numerator and (non-zero) denominator   expressed in their lowest terms. Rat objects are immutable. */class Rat is Comparable {    // Private helper function to check that 'o' is a suitable type and throw an error otherwise.    // Numbers and numeric strings are returned as rationals.    static check_(o) {        if (o is Rat) return o        if (o is Num) return Rat.fromFloat(o)        if (o is String) return (o.contains("_") && o.contains("/")) ? fromMixedString(o) :                                 o.contains("/") ? fromRationalString(o) : fromString(o)        Fiber.abort("Argument must either be a rational number, a number or a numeric string.")    }     // Private helper function which returns the greatest common divisor of 'n' and 'd'.    static gcd_(n, d) {        while (d != 0) {            var t = d            d = n % d            n = t        }        return n    }     // Private helper method which constructs a Rat object from a non-integral numeric string.    static fromDecimalString_(s) {        if (s.contains("e")) Fiber.abort("Argument is out of range.")        var ix = s.indexOf(".")        var dp = s[ix+1..-1]        var den = (10.pow(dp.count)).round        var num = Num.fromString(s[0...ix] + dp)        return Rat.new(num, den)    }     // Constants.    static minusOne { Rat.new( -1,  1) }    static zero     { Rat.new(  0,  1) }    static one      { Rat.new(  1,  1) }    static two      { Rat.new(  2,  1) }    static ten      { Rat.new( 10,  1) }    static half     { Rat.new(  1,  2) }    static tenth    { Rat.new(  1, 10) }     // Constructs a new Rat object by passing it a numerator and a denominator.    construct new(n, d) {        if (!(n is Num && n.isInteger)) Fiber.abort("Numerator must be an integer.")        if (!(d is Num && d.isInteger && d != 0)) {            Fiber.abort("Denominator must be a non-zero integer.")        }        if (n.abs > 9007199254740991) Fiber.abort("Numerator is out of range.")        if (d.abs > 9007199254740991) Fiber.abort("Denominator is out of range.")        if (n == 0) {            d = 1        } else if (d < 0) {            n = -n            d = -d        }        var g = Rat.gcd_(n, d).abs        if (g > 1) {            n = (n/g).truncate            d = (d/g).truncate        }        _n = n        _d = d    }     // Convenience method which constructs a new Rat object by passing it just a numerator.    static new(n) { Rat.new(n, 1) }     // Constructs a rational number from an integer.    static fromInt(i) { Rat.new(i, 1) }     // Constructs a rational number from a floating point number.    static fromFloat(f) {        if (!(f is Num)) Fiber.abort("Argument must be a number.")        if (f.isInteger) return Rat.new(f, 1)        var s = "%(f)"        return fromDecimalString_(s)    }     // Constructs a rational number from a numeric string.    static fromString(s) {        var n        if (!(n = Num.fromString(s))) Fiber.abort("Argument must be a numeric string.")        if (n.isInteger) return Rat.new(n, 1)        return fromDecimalString_(s.trim().trimEnd("0"))    }     // Constructs a rational number from a string of the form "n/d".    // Improper fractions are allowed.    static fromRationalString(s) {        s = s.trim()        var nd = s.split("/")        if (nd.count != 2) Fiber.abort("Argument is not a suitable string.")        var n = Num.fromString(nd[0])        var d = Num.fromString(nd[1])        if (!n || !d) Fiber.abort("Argument is not a suitable string.")        return Rat.new(n, d)    }     // Constructs a rational number from a string of the form "i_n/d" where 'i' is an integer.    // Improper and negative fractional parts are allowed.    static fromMixedString(s) {        var ind = s.split("_")        if (ind.count != 2) Fiber.abort("Argument is not a suitable string.")        var nd = fromRationalString(ind[1])        var i = Rat.fromString(ind[0])        var neg = i.isNegative || (i.isZero && ind[0][0] == "-")        return neg ? i - nd : i + nd    }     // Returns the greater of two rational numbers.    static max(r1, r2) { (r1 < r2) ? r2 : r1 }     // Returns the smaller of two rational numbers.    static min(r1, r2) { (r1 < r2) ? r1 : r2 }     // Private helper method to compare two integers.    static compareInts_(i, j) { (i - j).sign }     // Determines whether a Rat object is always shown as such or, if integral, as an integer.    static showAsInt     { __showAsInt }    static showAsInt=(b) { __showAsInt = b }     // Basic properties.    num        { _n }                // numerator    den        { _d }                // denominator    ratio      { [_n, _d] }          // a two element list of the above        isInteger  { toFloat.isInteger } // checks if integral or not    isPositive { _n > 0 }            // checks if positive    isNegative { _n < 0 }            // checks if negative    isUnit     { _n.abs == 1 }       // checks if plus or minus one    isZero     { _n == 0 }           // checks if zero     // Rounding methods (similar to those in Num class).    ceil     { Rat.fromInt(toFloat.ceil) }      // higher integer    floor    { Rat.fromInt(toFloat.floor) }     // lower integer    truncate { Rat.fromInt(toFloat.truncate) }  // lower integer, towards zero    round    { Rat.fromInt(toFloat.round) }     // nearer integer    fraction { this - truncate }                // fractional part (same sign as this.num)     // Reciprocal    inverse  { Rat.new(_d, _n) }     // Integer division.    idiv(o)  { (this/o).truncate }     // Negation.    -{ Rat.new(-_n, _d) }     // Arithmetic operators (work with numbers and numeric strings as well as other rationals).    +(o) { (o = Rat.check_(o)) && Rat.new(_n * o.den + _d * o.num, _d * o.den) }    -(o) { (o = Rat.check_(o)) && (this + (-o)) }    *(o) { (o = Rat.check_(o)) && Rat.new(_n * o.num, _d * o.den) }    /(o) { (o = Rat.check_(o)) && Rat.new(_n * o.den, _d * o.num) }    %(o) { (o = Rat.check_(o)) && (this - idiv(o) * o) }     // Computes integral powers.    pow(i) {        if (!((i is Num) && i.isInteger)) Fiber.abort("Argument must be an integer.")        if (i == 0) return this        var np = _n.pow(i).round        var dp = _d.pow(i).round        return (i > 0) ? Rat.new(np, dp) : Rat.new(dp, np)    }     // Returns the square of the current instance.    square { Rat.new(_n * _n , _d *_d) }     // Other methods.    inc { this + Rat.one }            // increment    dec { this - Rat.one }            // decrement    abs { (_n >= 0) ? this : -this }  // absolute value    sign { _n.sign }                  // sign     // The inherited 'clone' method just returns 'this' as Rat objects are immutable.    // If you need an actual copy use this method instead.    copy() { Rat.new(_n, _d) }     // Compares this Rat with another one to enable comparison operators via Comparable trait.    compare(other) {        if ((other is Num) && other.isInfinity) return -other.sign        other = Rat.check_(other)        if (_d == other.den) return Rat.compareInts_(_n, other.num)        return Rat.compareInts_(_n * other.den, other.num * _d)    }     // As above but compares the absolute values of the BigRats.    compareAbs(other) { this.abs.compare(other.abs) }     // Converts the current instance to a Num.    toFloat { _n/_d }     // Converts the current instance to an integer with any fractional part truncated.    toInt { this.toFloat.truncate }     // Returns a string represenation of this instance in the form "i_n/d" where 'i' is an integer.    toMixedString {        var q = _n / _d        var r = _n % _d        if (r.isNegative) r = -r        return q.toString + "_" + r.toString + "/" + _d.toString    }     // Returns the string representation of this Rat object depending on 'showAsInt'.    toString { (Rat.showAsInt && _d == 1) ? "%(_n)" : "%(_n)/%(_d)" }} /*  Rats contains various routines applicable to lists of rational numbers */class Rats {    static sum(a)  { a.reduce(Rat.zero) { |acc, x| acc + x } }    static mean(a) { sum(a)/a.count }    static prod(a) { a.reduce(Rat.one) { |acc, x| acc * x } }    static max(a)  { a.reduce { |acc, x| (x > acc) ? x : acc } }    static min(a)  { a.reduce { |acc, x| (x < acc) ? x : acc } }}`