feat(core): add fsharp init-template

[lucasschejtman]

Add F# init-template to the cli.

I followed the C# patterns, however, the solution file (.sln) doesn't reference the project file (.[cd|fs]proj) which in return doesn't reference the project files. That makes them quite unusable out of the box.

The proposed solutions would be

1. Add the proper references in the template files
2. Update the template instructions to include the relevant dotnet add commands.

Happy to create an issue and submit another PR to address it.

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Pull Request Checklist

• Testing
  • Unit test added (prefer not to modify an existing test, otherwise, it's probably a breaking change)
  • CLI change?: coordinate update of integration tests with team
  • cdk-init template change?: coordinated update of integration tests with team
• Docs
  • jsdocs: All public APIs documented
  • README: README and/or documentation topic updated
• Title and Description
  • Change type: title prefixed with fix, feat will appear in changelog
  • Title: use lower-case and doesn't end with a period
  • Breaking?: last paragraph: "BREAKING CHANGE: <describe what changed + link for details>"
  • Issues: Indicate issues fixed via: "Fixes #xxx" or "Closes #xxx"
• Sensitive Modules (requires 2 PR approvers)
  • IAM Policy Document (in @aws-cdk/aws-iam)
  • EC2 Security Groups and ACLs (in @aws-cdk/aws-ec2)
  • Grant APIs (only if not based on official documentation with a reference)

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license.

[eladb]

@costleya can you please take a look here?

[Doug-AWS]

If F# has any additional or different prerequisites compared to C#, please enumerate them and ping me by adding Doug-AWS to the comment. Here is what I have for C#:

.NET standard 2.0 compatible implementation:

.NET Core >= 2.0
.NET Framework >= 4.6.1
Mono >= 5.4

[lucasschejtman]

@Doug-AWS Same requirements, although there are some workarounds at the compiler level for FSI support, F# sits on top on .NET Standard 2.0 since 4.3.1.

[costleya]

I'm going to change the C# cdk.json template to:

"app": "dotnet run --project HelloCdk/HelloCdk.csproj"

To eliminate the need to remember to recompile the application every time before you run "cdk *". Feel free to make this change now, or I can make it when I update the C# one.

[lucasschejtman]

I'll update it after the C# one.
Do you have an opinion on my comments at the beginning regarding the solution not referencing the project and the project not referencing the project files? They're not very useful in their current state, happy to update those as well.

[costleya]

Thanks for calling this out.

The C# template adds the project after generation using the add-project.hook.ts. I see you copied this file, but did not update it for the F# template. Try changing the "dotnet add" command to point to the fsproj, and see if it works. I added the comments to the lines that need to change.

[lucasschejtman]

This still doesn't address the missing project files in the project file (HelloCdk.[c|f]sproj),
could add the logic to the add-project.hook.ts file in another PR.

Also, dotnet restore is not automatically done in all IDEs so it could be added as another post template init logic like we do with npm and maven.

[costleya]

I'm confused about what is missing. The add-project hook calls dotnet add. If there are additional resources missing for F# on the project level, then you can either add those references into the template, or you can take care of it in the/a hook.

The dotnet restore is definitely something that could be added.

[lucasschejtman]

@costleya My bad, forgot they changed it in the last version of the framework, you don't need to add files to project now. It's directory based now.

Happy to add the dotnet restore bit in a separate PR to not pollute this one.

[costleya]

Sounds like a plan.

[costleya]

Thanks for calling this out.

The C# template adds the project after generation using the add-project.hook.ts. I see you copied this file, but did not update it for the F# template. Try changing the "dotnet add" command to point to the fsproj, and see if it works. I added the comments to the lines that need to change.