have cabal init create Main.hs

[cdepillabout]

I often use cabal init when creating a new package, often before I've even started writing any code. Using cabal-install version 1.20.0.4, it doesn't seem like cabal init will create Main.hs for you, even if it doesn't already exist.

It would be nice cabal init created a short Main.hs for you, if it doesn't already exist.

Ideally, I'd like to be able to have the following workflow:

# make a new directory for my project
$ mkdir my-project && cd my-project

# initialize my sandbox
$ cabal sandbox init
...

# create the .cabal file
$ cabal init
...

# cabal init would have created a Main.hs like below
$ cat Main.hs
module Main where

main = putStrLn "Hello World!"

# now, you can immediately run `cabal install`
$ cabal install
...

# this produces an executable that you can immediately run
$ ./.cabal-sandbox/bin/my-project
Hello World!
$

If I were to send a pull request for this, would there be any interest in it?

[23Skidoo]

/cc @byorgey

[cdepillabout]

This feature would of course need to work well with #1989.

[fujimura]

In my understanding, cabal init is a command to cabalise the exisiting project. So, generating files are a bit different from original purpose.

Aside from original purpose, I think if cabal init generates sufficient files to start new project, it'd be helpful for many developers.

[byorgey]

Yes, I don't think this really fits with the purpose of cabal init. @cdepillabout , perhaps you would be interested in a project like https://github.com/fujimura/hi which seems to be more what you are looking for.

[cdepillabout]

@byorgey, you're right. hi is really nice and it could definitely be used for what I want, but it's a little "heavy" for just generating a Main.hs file.

I realize that cabal init was originally used for cabalizing an existing Haskell project, but I almost always end up using it before I actually write any Haskell code. For my specific use case, it would be nice if it created a Main.hs for me.

Maybe I should seriously look into using hi to generate projects instead of cabal init.

[byorgey]

@cdepillabout , if hi is too heavyweight, you could just write a little script that calls cabal init and then copies a fresh Main.hs into the directory.

[cdepillabout]

That's true, I'll look into doing that.

[cgag]

Is the purpose really to cabalize existing non-cabal projects? I might be wrong but I feel starting new projects with "cabal init" has to be a way more common use-case. Creating a working project from "cabal init" seems like a very nice thing to have, especially for beginners.

[23Skidoo]

Perhaps init should have two modes of operation. When run in an empty directory, init could default to the "new project" mode, and in a non-empty one to "cabalize" mode.

[erikd]

I think @23Skidoo's ideas of two modes is a good. Personally, "cabalize" an existing project is by far my most common use case.

[bitemyapp]

Two modes...could be okay. I'm a little iffy on it. The overloading of commands is already getting to be a bit much.

I'm the opposite of @erikd - cabal init is usually my first command. It's possible that an official templating function could help here. Some exist already but aren't widely known.

[cdepillabout]

@bitemyapp, I'm the same as you.

As for a templating function, have you tried hi mentioned above? It is what you're looking for?

What I'd like more than a templating function is just something that creates Main.hs so I can run cabal run (or cabal install) right away. For my personal use-case it doesn't have to be a templating function.

[cgag]

I'm not actually sure why it would need two different modes. While I think cabal init is probably most common use-case, this seems like an improvement for both uses. When "cabalizing" a project, I imagine you'd already have a main that already exists, so this wouldn't affect things. If you didn't, I imagine you'd need to create one as well.

Re: hi templating, I'd like it if cabal just did templating. I know lein (Clojure) does it, and I believe it's being considered by Cargo (rust) as well.

[byorgey]

Well, perhaps you are all right, having cabal init just create a simple Main.hs if one does not already exist would be useful. I will reopen this issue; pull requests welcome.

[cdepillabout]

This has been implemented and merged in #2483. Thanks!