The Prompt

[Noventrice]

When I went through LYAH a few years ago the prompt showed which modules were being used. I think the Linux distro I used at the time installed ghci with a custom prompt. I think the prompt showing which modules are being used is helpful for a tutorial. I have notes which go halfway through chapter 13 that use this prompt. I found another thing I could change in my notes, but I need to know if I can write the prompt differently first.

Here is an example:
ghci Data.Char> all isAlphaNum "bobby283"
True

IsAlphaNum isn't available unless you import it. Some people don't like this prompt because it can make the prompt crowded. But, I think it is fine for a tutorial.

You can get this custom prompt by putting the following code in your .ghci file:
:set prompt "%s> "

[ulysses4ever]

Since it's a Q&A category, do you have an actual question?

[Noventrice]

Can I modify the prompts in the tutorial?

[ulysses4ever]

I'm not sure at which point the list of modules was removed: it seems that this repository imported a version without the lists already. Recently, #32 was merged that continued in that direction and removed Prelude in one place. The reasoning being that GHC 9.2 doesn't print the list of modules by default anymore. I lean towards following the newer GHC here.

Also, you mention GHC installation from some Linux distro repository. Since #24 we recommend GHCup, which, if used, gives you GHC 9.2 by default these days -- consistent with the decision to remove the module lists.

[MatthijsBlom]

Here are some alternative strategies:

• Teach that GHCi commands exist. Relevant here, I guess, are :browse and :show modules. But more generally knowing about :help is useful. (There are GHCi commands that allow changing the prompt to the old default.)

• If having stuff not in scope is a recurring problem for readers, perhaps finding stuff should be emphasized more. At present, Hoogle is mentioned only once, in chapter 7.