ForSyDe-Shallow

A Framework for Modeling Heterogeneous Systems

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1

Starting a new ForSyDe-Shallow project

This short tutorial describes how to start a new ForSyDe-Shallow project for the cross-platform build-tool Stack and can make use from editors that support the language server protocol. In this example, we use Linux and the editor emacs. Please, adapt the tutorial to your tool environment.

This demo show some of the capabilities of the Haskell Language Server.

Preparation: Installation of the Haskell tools

Setup the Haskell environment as outlined on the Get started tutorial on the web pages for the Haskell language.

Create a new ForSyDe project with Stack

NOTE: The following steps will result in a ForSyDe project structure. If used with an editor that supports the language server protocol, a lot of useful information will be received from the editor during development time. The final outcome of the following steps will result in a project structure similar to this one, where the copyright and license information has been removed. For a new project, please follow the steps below and do not just copy the zip-file. This ensures that you also have the correct copyright and license information. For this tutorial, we have used the ghc-version 9.4.8 (LTS 21.25).

Create a new Haskell-project with the Haskell build tool Stack. You can choose any name, here forsyde-project is chosen as project name.
```
prompt> stack new forsyde-project
```

Enter the project directory

prompt> cd forsyde-project/
prompt> ls
app  CHANGELOG.md  forsyde-project.cabal  LICENSE  package.yaml  README.md  Setup.hs  src  stack.yaml  test

Open the file package.yaml in your editor and add a line - forsyde-shallow >= 3.5.0.0 under dependencies:.
```
dependencies:
- base >= 4.7 && < 5
- forsyde-shallow >= 3.5.0.0
```
Open the file stack.yaml in your editor. Uncomment the first extra-deps: entry and add a line - forsyde-shallow-3.5.0.0 under extra-deps:
```
extra-deps: 
- forsyde-shallow-3.5.0.0
```
Create a Haskell file for your new ForSyDe model.
```
emacs src/ForSyDeModel.hs
```

Open the file src/ForSyDeModel.hs and enter the following code:

module ForSyDeModel where

import ForSyDe.Shallow

adder = zipWithSY (+)

Assuming you use an editor that uses the language server protocol (LSP). If the module ForSyDe.Shallow is not found, check that your global configuration uses the same stackage release version. Open the global stack project file (NOTE: Here we give the location for Linux, however, for other operating systems the location might differ, check on the Stack YAML configuration page, where the global configuration file is stored. For Windows, to find the global stack project file you need to find the location of the Stack root using stack path in PowerShell. There you can find the stack.yaml file.)
```
prompt> less ~/.stack/global-project/stack.yaml
...
packages: []
resolver: lts-21.25
...
```
and check which stackage release is used. Check the resolver entry. For the LSP-protocol, the editor will work with the global stack configuration, so it is important that the global and the project stackage version are identical.

If you have created a new project, very likely the stack version of the local project file needs to be changed. So, in this case check the local stack.yaml file and check under resolver: which version is used.
```
 prompt> 
 ...
 resolver:
     url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/22/5.yaml
 ...
```
Change the resolver entry to the version in your global stack configuration file and save it. In our case the new resolver entry in the local stack.yaml file needs to be the following.
```
...
resolver: lts-21.25
...
```
The editor might still not detect the module ForSyDe.Shallow using the haskell-language-server with your editor, it is often necessary to generate a hie.yaml file. This can be done by running the program gen-hie, which can be installed with stack.
```
stack install implicit-hie
```
Then in the top-level of your project, you can generate the hie.yaml file.
```
 gen-hie > hie.yaml
```
Now, the editor should be able to detect the ForSyDe.Shallow module.
Close the editor and reopen your ForSyDe model src/ForSyDeModel.hs. For VSCode it is also required that you run in ‘Trusted Mode’, please double-check that you do not run in restricted mode.

You should now be able to see some suggestions in the editor. If you hover about Haskell or ForSyDe functions and will see more detailed information about these functions.
Cleaning (Optional): When creating a new project with the command stack new, additional directories and files have been created which are not needed for modelling a ForSyDe system, which we normally create as a library and not as an executable. To remove the unnecessary directories and files, the following needs to be done.
- Remove the unnecessary directories and files.
```
  prompt> rm src/Lib.hs
  prompt> rm -rf app
```
- Open package.yaml and remove the complete entry executables: and its content.