It seems that we really want is something like Idris's `:doc` command:

Idris> :doc map
Prelude.Functor.map : Functor f => (m : a -> b) -> f a -> f b
    Apply a function across everything of type 'a' in a
    parameterised type
    
    The function is Total
 

Idris> :doc length
Prelude.List.length : List a -> Nat
    Compute the length of a list.
    
    Runs in linear time
    
    The function is Total
Prelude.Strings.length : String -> Nat
    Returns the length of the string.
    
        > length ""
        0
    
        > length "ABC"
        3
    
    The function is Total

I don't like the idea of making `:type` more complicated, and I think this would satisfy the need for understanding much more effectively.

Matt Parsons

On Thu, Apr 28, 2016 at 3:35 PM, Daniel Díaz <diaz.carrete@gmail.com> wrote:
I like the flag idea mentioned by Eric Seidel:

> Perhaps instead of changing the default behavior of :type or adding new
commands, we could add a flag to enhance :type's output.

Would it be overkill to have two flags, one that enabled showing the full type + specializations, and a "newbie mode" flag that only showed a few specializations?

Daniel.

On Wednesday, April 27, 2016 at 2:34:29 PM UTC+2, Takenobu Tani wrote:
Dear cafe,

I'm forwarding mail from ghc-devs ML [1].

I think `:type` command is very important for beginners and middle users.
Please feedback your opinion to them ;)



> 2016-04-26 22:08 GMT+09:00 Richard Eisenberg <e...@cis.upenn.edu>:
> Hi devs,
> 
> Over the weekend, I was pondering the Haskell course I will be teaching next year and shuddered at having to teach Foldable at the same time as `length`. So I implemented feature request #10963 (https://ghc.haskell.org/trac/ghc/ticket/10963), which allows for a way for a user to request a specialization of a type. It all works wonderfully, but there is a real user-facing design issue here around the default behavior of :type and whether or not to add new :type-y like commands. I have outlined the situation here: https://ghc.haskell.org/trac/ghc/wiki/Design/GHCi/Type
> 
> I'd love some broad input on this issue. If you've got a stake in how this all works, please skim that wiki page and comment on #10963.
> 
> Thanks!
> Richard

Cheers,
Takenobu


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