Functional Programming Patterns(slideshare.net)

    var algebra = require('algebra');
    
    var M = algebra.MatrixSpace;
    var R = algebra.Real;
    
    // Create the space of 2x2 real matrices
    var R2x2 = new M(R, 2);
    
    // Create two invertible matrices:
    //
    //       | 1 2 |         | -1 0 |
    //       | 3 4 |   and   |  0 1 |
    //
    var m1 = new R2x2.Matrix([1, 2,
                              3, 4]);
    
    var m2 = new R2x2.Matrix([-1, 0,
                               0, 1]);
    
    // Multiply m1 by m2 at right side
    //       | 1 2 | * | -1 0 | = | -1 2 |
    //       | 3 4 |   |  0 1 |   | -3 4 |
    m1.mul(m2);
    
    console.log(m1.data); // [-1, 2, -3, 4]
    
    // Check out m1 determinant, should be 2 = (-1) * 4 - (-3) * 2
    console.log(m1.determinant.data); // 2

    > import Text.Regex.PCRE.Light
    > let numberRgx = compile "[0-9]+" []
    > match numberRgx "the answer is 42" []
    Just ["42"]

    ghci> [$rx|[0-9]+|] "the answer is 42"
    Just ["42"]