Tutorial: compile F# with the native executable

Use the AOT morphir executable and the F# frontend extension, for build agents without the dotnet tool

Acme’s build agents run the native morphir executable: one file, fast to start, and no dotnet tool setup. The native executable has no F# compiler inside. It runs the F# frontend as an extension, a separate process that it talks to over the Morphir Extension Protocol (MEP).

sequenceDiagram
    participant M as morphir compile
    participant G as morphir-fsharp-frontend
    M->>G: initialize (agree IR versions)
    M->>G: compileModel (F# documents)
    G-->>M: Morphir IR
    M->>G: shutdown, exit

This tutorial uses the project from the F# pricing tutorial (examples/car-rental-pricing).

1. Install the executable and the extension

Download morphir for your platform from the releases page: morphir-linux-x64, morphir-linux-arm64, morphir-osx-arm64 or morphir-win-x64.exe.

VERSION=0.4.0-alpha.3   # the release you want
curl -fsSL -o morphir \
  "https://github.com/finos/morphir-dotnet/releases/download/v$VERSION/morphir-osx-arm64"
chmod +x morphir && mv morphir /usr/local/bin/

The F# frontend extension is a dotnet tool. It needs the .NET 10 runtime.

dotnet tool install --global Morphir.Frontend.FSharp.Extension --prerelease

2. Try it without the extension

cd acme
morphir compile

error compile.frontend_unavailable: No registered frontend reads the language 'fsharp'. This build registers no frontend. The self-contained and framework-dependent morphir and dotnet-morphir have a built-in F# frontend; this offering uses the F# frontend process delivery morphir-fsharp-frontend. Set [frontend.fsharp].extension in morphir.toml, or use --extension, to configure a frontend extension.
compile failed (configuration, exit code 2); 1 error(s): error compile.frontend_unavailable

3. Compile with the extension

morphir compile --extension morphir-fsharp-frontend

compile succeeded: 3 module(s), IR version 4, /work/acme/.morphir/out/compile.dest/morphir-ir.json; no diagnostics
/work/acme/.morphir/out/compile.dest/morphir-ir.json

The IR is the same, byte for byte, as dotnet-morphir compile writes. Classic IR versions work too:

morphir compile --extension morphir-fsharp-frontend --ir-version 2

4. Put it in morphir.toml

So that nobody has to remember the option, add the extension to the F# table:

[frontend.fsharp]
project_file = "Acme.CarRental.fsproj"
extension = "morphir-fsharp-frontend"

morphir compile --json | jq '{success, frontend, extension: .origins.extension.key}'

{
  "success": true,
  "frontend": "org.finos.morphir.fsharp-frontend (mep)",
  "extension": "frontend.fsharp.extension"
}

(mep) shows that the extension did the work. --extension on the command line wins over the key. The value can be a command on PATH, a path, or a .dll, which runs on the dotnet host.

5. When the extension is missing

error extension.unavailable: Extension morphir-fsharp-frontend did not start: An error occurred trying to start process 'morphir-fsharp-frontend' with working directory '/work/acme'. No such file or directory
compile failed (configuration, exit code 2); 1 error(s): error extension.unavailable
CodeFix
extension.unavailableInstall the extension, or check that it is on PATH.
extension.not_admittedRequest an IR version that the extension serves (1 to 4).
extension.protocol_errorUpdate the extension.
extension.timeoutRead the extension’s messages on stderr, then run again.

Limits

  • .fsi signature files: the extension reads .fs files only. Use dotnet-morphir for a project with signature files.
  • generate, validate and the rest of the commands are the same in both executables.

Next: the compile reference, or how the F# frontend runs as an extension.


Last modified November 10, 2026: docs(compile): quote the Native AOT refusal with its new F# frontend hint (eafc4edd)