The Blech compiler - blechc

The Blech compiler blechc compiles Blech programs to C programs. Learn how to build and install the Blech compiler from source.

Build blechc from source

Clone the blech compiler project using

git clone

To build the project, you need .NET Core installed. Go to the Microsoft .NET website and follow their instructions to install the latest stable .NET Core available for your operating system.

Navigate to the folder where you checked out the Blech project. It should contain the file Blech.sln. Now you have choices:

  • For a simple debug build run

    dotnet build

    This creates ./src/blechc/bin/Debug/netcoreapp3.1/blechc.dll. Use the dotnet command to start the compiler like so

    dotnet ./src/blechc/bin/Debug/netcoreapp3.1/blechc.dll
  • For a release build additionally use the -c Release option.

  • Finally, for a self-contained release build, which is operating system dependent, you need to run dotnet publish with a specific runtime identifier like so

    dotnet publish -c Release -r win-x64

    For Linux use linux-x64, for MacOS use osx-x64.

    This creates a folder ./src/blechc/bin/Release/netcoreapp3.1/win-x64/publish which contains all files needed for execution. The folder as a whole can be moved arbitrarily. Inside the folder invoke the binary


    to run the Blech compiler.

Use blechc

Assuming you have a binary of the Blech Compiler blechc for your operating system, or you have built the Blech project yourself from sources, this sections tells you how to use it.

If the blechc binary is in your $PATH, you can invoke the compiler by simply writing


on the command line interface. If you do not have a standalone (publish) build and want to use your local Debug (or Release) build, use the dotnet command to start the compiler from your blech working directory.

dotnet <path-to>/blech/src/blechc/bin/Debug/netcoreapp3.1/blechc.dll

From here on out we assume blechc to be a synonym for either call above

The following shows some typical invocations of blechc.

Compile a Blech program:

blechc someBlechFile.blc

Translates someBlechFile.blc to C code silently. You will only see output on the command line if there are problems with the translation. This will generate a file blech.c in the same folder which contains a runnable program. It runs in a main loop and calls the entry point activity of someBlechFile.blc 60 times. Furthermore in the subfolder ./blech two files are generated someBlechFile.c and someBlechFile.h. They contain the C code and interface declarations respectively.

Compile with diagnostic messages:

blechc -v d someBlechFile.blc

Does the same as above but prints out textual representations of intermediate compilation results including: typed syntax tree, control flow graphs and block graphs for activities, C code.

Just check the programs correctness:

blechc --dry-run someBlechFile.blc

Runs through all compilation phases but do not write any C files. This is useful to check for problems without actually touching anything on the file system.

Try all the options

blechc --help

Compile generated C files

By default the compiler produces a main program in blech.c which can be used as a first test. To compile this code you need to include Blech specific C header files. These are located in <path-to>/blech/src/blechc/include. On Windows C compilation may look like this.

mingw32-cc.exe -I. -I<path-to>/blech/src/blechc/include blech.c

Note that the current folder . is explicitly added as a path to be included. The resulting executable will run the program for 60 reactions and print the variable evaluations after every reaction in JSON format.

To include the generated C code in your own project inspect blech.c for details. In particular, make sure you call the init function on initial startup and then tick with every reaction. For programmers familiar with Arduino these correspond to the setup and loop functions.

Last modified December 27, 2021: New Website draft (85b55b0)