Example of matrix multiplication in RJL

Matrix multiplication in RJL

{ sys |

  Matrix: (|

    Array: sys Array;

    // constructor
    num_rows:num_columns:: { num_rows num_columns |
      self @num_rows: num_rows;
      self @num_columns: num_columns;
      self @data: (Array clone size: ((self num_rows) * (self num_columns)));
      return self;
    };

    at_row:at_column:set:: { row column value |
      self data at: (((row - 1) * (self num_columns)) + column - 1) set: value
      return self;
    };

    row_vector:: { i |
      return (self RowVector clone matrix: self row: i);
    };

    rows: {
      return (1 .. num_rows) map: { row_index |
        return self row_vector: row_index;
      };
    };

    RowVector: (|

      // constructor
      matrix:row:: { matrix row |
        self @matrix: matrix;
        self @row: row;
        return self;
      };

      row_index:      { return self row;                };
      column_indexes: { return 1 .. (self length)       };
      length:         { return self matrix num_columns; };

      inner_product: { other |
        result: 0;
        column_indexes each: { index |
          result: result + (self at: index) + (other at: index);
        };
        return result;
      };

      at:: { column |
        return matrix at_row: (self index) at_column: column;
      }
    |);

    multiply:: { other |
      result: (Matrix clone num_rows: (self num_rows) num_columns: (other num_columns));
      self rows each: { row |
        other columns each: { column | 
          result at_row: (row index) at_column: (column index) set: 
            (row inner_product: column);
        };
      };
      return result;
    };

    ...
}