Re: [Haskell-cafe] GHCI Feature Request: Last Successful Compilation State Saved

Oh, I didn't reply all. Whoops. On 28 August 2011 13:40, Christopher Done wrote:

On 27 August 2011 22:59, aditya siram wrote:

...

I would like for the GHCI interpreter to save its environment before reloading a file and allowed the user to revert back to that state if the compilation was unsuccessful.

Many times I've changed files, loaded them, hit a compilation error and needed, for example, the inferred type signature of some function. Even though that function hasn't been changed I have to either fix my code, undo a bunch of changes or comment out the last change I made and reload in order to do a ":type" on the function. This really breaks the flow of development.

This has been bugging me for a long time and it's been on my TODO list for haskell-emacs: https://github.com/chrisdone/haskell-emacs

I just implemented it. http://i.imgur.com/A71T5.png

I just run two ghci processes, one for compiling, one for merely loading the code in when the former succeeds.

It's not a very pleasant hack but in conjunction with :set -fobject-code it is fast and does not consume that much more memory. Considering tibbe's report is 4 years old, I think this solution is better than nothing.

Set hs-config-preliminary-load-file to t in hs-config.el and it will do a preliminary load in a separate GHCi process.