Create README.md

README.md

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+# blt-gp
+Genetic Programming (GP) library for C++. Integrates directly into the C++ type system, a safe replacement for lilgp without performance compromises.
+
+## Easy to use, Safe, and fast, all without compromise
+Using blt-gp is very easy, import the program header, define your operators, and then call the relevant functions to set up the program to your liking. 
+Concrete examples can be found in the example folder and compiled using the CMake argument `-DBUILD_EXAMPLES=ON`
+
+Operator example:
+```c++
+// constructor takes an optional string that describes the function of the operator. Used in printing.
+blt::gp::operation_t add([](float a, float b) {
+  return a + b;
+}, "add");
+```
+Operators can return different types or have differing types as arguments, this will automatically be recognized by the library.
+```c++
+// Any callable type can be passed as the function parameter
+// so long as the function exists for the lifetime of the gp_program object.
+bool compare_impl(bool type, float a, float b)
+{
+  return type ? (a > b) : (a < b);
+}
+
+
+blt::gp::operation_t compare(compare_impl, "compare");
+```
+Please note that if a type doesn't have a way to produce a terminal, or doesn't have a way of converting from a type that has a terminal, you will get an error.
+
+Defining your fitness function is just as easy:
+```c++
+const auto fitness_function = [](blt::gp::tree_t& current_tree, blt::gp::fitness_t& fitness, blt::size_t current_index) {
+    // evaluate your fitness
+    // ...
+    // write to the fitness out parameter. Only "adjusted_fitness" is used during evaluation.
+    fitness.raw_fitness = static_cast<double>(fitness.hits);
+    fitness.standardized_fitness = fitness.raw_fitness;
+    // higher values = better. Should be bounded [0, 1]
+    fitness.adjusted_fitness = 1.0 - (1.0 / (1.0 + fitness.standardized_fitness));
+    // returning true from this function ends the evaluation of the program, as this signals that a valid solution was found.
+    // this function is allowed to return void.
+    return static_cast<blt::size_t>(fitness.hits) == training_cases.size();
+};
+```