Re: [Haskell-cafe] Fw: Bikeshedding request for GHCi's :type

28 Apr 2016

      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  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 ;)
[1]: https://mail.haskell.org/pipermail/ghc-devs/2016-April/011933.html
...
2016-04-26 22:08 GMT+09:00 Richard Eisenberg :
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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