To generate the F# server stub for Azure Functions given an OpenAPI/Swagger specification file, please follow 3 simple steps below:

1. Download the Java JAR (https://oss.sonatype.org/content/repositories/snapshots/org/openapitools/openapi-generator-cli/4.1.3-SNAPSHOT/openapi-generator-cli-4.1.3-20190924.112244-39.jar)

2. Rename the JAR as "openapi-generator-cli.jar"

3. Run the following command to generate server stub for F#/Azure functions for the Petstore API (https://raw.githubusercontent.com/OpenAPITools/openapi-generator/master/modules/openapi-generator/src/test/resources/2_0/petstore.yaml):

Mac/Linux:

$ java -jar openapi-generator-cli.jar generate -g fsharp-functions -i https://raw.githubusercontent.com/OpenAPITools/openapi-generator/master/modules/openapi-generator/src/test/resources/2_0/petstore.yaml -o /var/tmp/fsharp-functions/

Windows:

$ java -jar openapi-generator-cli.jar generate -g fsharp-functions -i https://raw.githubusercontent.com/OpenAPITools/openapi-generator/master/modules/openapi-generator/src/test/resources/2_0/petstore.yaml -o C:\tmp\fsharp-functions

If you've any feedback or question, please let us know via https://github.com/OpenAPITools/openapi-generator/issues/new

Thanks again for the new generator by Nick Fisher (https://twitter.com/NickFisherAU)

Ref: https://github.com/OpenAPITools/openapi-generator/pull/3933