Question

Why might the C# language designers not have included support for something like this (ported from Structure and Interpretation of Computer Programs, second ed., p. 30):

/// <summary>Return the square root of x.</summary> double sqrt(double x) {   bool goodEnough(double guess) {     return Math.Abs(square(guess) - x) < 0.001;   }   double improve(double guess) {     return average(guess, x / guess);   }   double sqrtIter(double guess) {     return goodEnough(guess) ? guess : sqrtIter(improve(guess));   }   sqrtIter(1.0); } 

Answer 1

In fact, C# has exactly this.

double sqrt(double x) {     var goodEnough = new Func<double, bool>(guess =>         Math.Abs(square(guess) - x) < 0.001     );     var improve = new Func<double, double>(guess =>         average(guess, x / guess)     );     var sqrtIter = default(Func<double, double>);     sqrtIter = new Func<double, double>(guess =>         goodEnough(guess) ? guess : sqrtIter(improve(guess))     );     return sqrtIter(1.0); }