churn

What it does

churn transpiles INTERCAL source to C#, then compiles that to a .NET assembly with csc. It does not interpret — it produces a standalone .exe (or .dll) that runs on the .NET runtime.

Building churn from source requires the .NET 10 SDK:

dotnet build intercal64.sln

This builds churn.exe, the runtime, the DAP debug adapter, and compiles syslib64.dll from INTERCAL source automatically.

Compiling a program

A single file compiles to a single executable:

churn hello.i        # -> hello.exe
./hello.exe

Use the - prefix for flags, never / — Windows reinterprets / as a drive path.

Compiling multi-file projects

Source files are consumed in order and compiled into a single executable. List every file, and churn stitches them into one program:

churn main.i knight_attacks.i clear_mask.i center_dist.i    # -> main.exe

This is how the real programs are built. The Knight's Tour solver is roughly 570 lines across six source files; the Hilbert-curve geographic index spreads its lookup tables, coordinate data, and sort routines across eight. Each is a single churn invocation listing the files in order.

Labels are global across the combined source, so a routine defined in one file can be reached with DO (label) NEXT from another. This is also why 64-bit labels matter: with every file sharing one namespace, low-numbered labels clash. Prefer labels above INT_MAX for anything reusable.

Compiler flags

Flag	Effect
-t:library	Compile to a .dll instead of an executable
-r:name.dll	Link against a library assembly
-debug+dap	Enable the DAP debugger
-noplease	Disable the politeness check
-b	Brief output — suppress the banner

Linking libraries

Build a library from INTERCAL source with -t:library (all labels are exposed publicly by default; every code path must terminate in RESUME or GIVE UP). Then reference it when compiling a program:

churn -t:library syslib64.ic64          # build the library
churn -r:syslib64.dll stable_marriage.i # link and compile

See the Libraries page for the routines syslib64 provides.

Cross-language interop

INTERCAL libraries can be consumed from C#, and C# libraries from INTERCAL. A C# extension DLL exposes an entry point that INTERCAL reaches with DO…NEXT:

using INTERCAL.Runtime;

[assembly: EntryPoint("(3000)", "CSIntercalLib", "foobar")]
public class CSIntercalLib
{
    public bool foobar(ExecutionContext ctx)
    {
        ctx[".3"] = ctx[".2"] + ctx[".1"];
        return false;
    }
}

Because a language that can add is a language that has given up.

Across component boundaries

churn compiles to .NET assemblies, and NEXT / RESUME / FORGET work across them via a thread-pool execution model — so INTERCAL's stack semantics, where FORGET can drop entries from the middle of the call stack, hold even across assembly boundaries. Three constructs stay local, however:

• COME FROM — may only target a label in the current component.
• ABSTAIN / REINSTATE — act only on the local component, gerunds included.
• IGNORE / REMEMBER — cannot target labels in other components.