Letter is a compiler project built in TypeScript using the llvm-bindings module. The parser is based off of lectures by Dmitry Soshnikov. Letter compiles to LLVM IR, which can then be compiled with Clang.
Letter is functional-only at the moment, though the parser supports objects and I plan on implementing them.
Since Letter compiles using LLVM, it is compatible with C and C++. This hasn't been tested much, but there's an example of a Letter function being called from a C program in the /example/c-link/ folder.
Letter requires an installation of LLVM 13. The llvm-bindings readme has good installation instructions.
Features that are working now:
- Main function as entry point
- Preprocessor (import, define)
- Math operations
- Extern functions
- Function definitions
- Void type
- Overloading
- If statements
- Implicit typecasting of numbers
- Printing values using print.lt (printf wrapper)
- Strings, Floats, Doubles, Booleans, Integers
Use:
The released version is outdated: I'll update this when there's a release with LLVM working fully. For now, it must be run from node.
Run the compiler using npm run compile <filename>. This will run letter and clang, prividing an executable.
To build an object file, run npm run object <filename>.
The below flags don't work with this command - only with npx ts-node ./letter.ts -f <filename> <flags> which will generate llvm IR.
You then need to compile this IR using clang.
Current flags available: Tested:
-s, --stack: Prints the full JS stack on error. Normally, errors just print the message without stack trace when no debug flags are set.-t, --tokens: Prints a list of all tokens in the program, including from imported files.-a, --ast: Prints the full program's AST representation in JSON.-i, --emit-ir: Emits LLVM IR for compilation.
Untested with new versions:
-m, --minify: Combines all code into one file, and turns it into one line.- Recommended use:
./bin/letter.rdp -f filename --minify > file.min.lt
- Recommended use:
Sample programs and are included in the /example/ folder.