README.md

Compile Time Dynamic Language

Aim of project:

Implement a dynamically typed language in C++ that is evaluated 100% at compile time.

Example Usage

main.cpp contains the following working example:

// pseudo code example
/*
x = 6
y = 2 + x
z = (y * 10) + 7
text = "Hello "
text2 = text + "World!"
bool = !true
ifmodified = false
if 1:
   temp = 10
   ifmodified = true
*/


// equivalent code in C++ here | entirely evaluated at compile time
using code = Execute<TypeStackEmptyNode,
                     Assign<"x", Val<6>>,
                     Assign<"y", Apply<std::plus<>, Val<2>, Var<"x">>>,
                     Assign<"z", Apply<std::plus<>, Apply<std::multiplies<>, Var<"y">, Val<10>>, Val<7>>>,
                     Assign<"text", ValStr<"Hello ">>,
                     Assign<"text2", Apply<std::plus<>, Var<"text">, ValStr<"World!">>>,
                     Assign<"bool", Apply<std::logical_not<>, Val<true>>>,
                     Assign<"ifmodified", Val<false>>,
                     If<Val<1>, 
                        Assign<"temp", Val<10>>,
                        Assign<"ifmodified", Val<true>>>>;


// tests
static_assert(SymbolTableGetValue<NONE, code::values, "x">::value == 6); // basic non modified variable init
static_assert(SymbolTableGetValue<NONE, code::values, "y">::value == 8); // basic evaluation of expression using Apply and ID lookup using Var
static_assert(SymbolTableGetValue<NONE, code::values, "z">::value == 87); // chained expression test
constexpr string_literal teststring = "Hello World!";
static_assert(SymbolTableGetValue<NONE, code::values, "text2">::value == teststring); // string concat test
static_assert(!SymbolTableGetValue<NONE, code::values, "bool">::value); // bool test
static_assert(SymbolTableGetValue<NONE, code::values, "temp">::value == NONE); // GOOD we lose values on the temp if scope
static_assert(SymbolTableGetValue<NONE, code::values, "ifmodified">::value); // GOOD we successfully modified variable in outer scope

Approach

The language will be implemented as a tree-walk interpreter which makes use of nodes that perform operations.

Compiler

GCC-11 /std:c++20

Milestones:

1. Implement basic chainable expressions such as binary ops for float/number types ✔️
2. Implement variables using lookup table. ✔️
3. Implement boolean and string types. ✔️
4. Implement basic error messages for type related errors to expressions.
5. Implement basic control flow through if statements. ✔️
6. Implement for loops.
7. Implement methods.
8. Have language parsed through string literal instead of type declarations.