New type of ($) operator in GHC 8.0 is problematic

George Colpitts george.colpitts at gmail.com
Mon Mar 28 13:22:59 UTC 2016


Was there any consensus on how to move forward on this? I just found
another example of
​​
8.0 type which is not beginner friendly:

bash-3.2$ ghci
GHCi, version 8.0.0.20160204: http://www.haskell.org/ghc/  :? for help
Prelude> True
True
it :: Bool
Prelude> True || undefined
True
*it :: ?callStack::GHC.Stack.Types.CallStack => Bool*



On Wed, Mar 2, 2016 at 1:56 PM Ericson, John <john_ericson at brown.edu> wrote:

> I dispute your second point a bit: I consider any Prelude changes a
> standard library change than a language change, not withstanding the fact
> the Prelude is imported by default. Any beginner-language library can still
> be imported from normal code. Likewise a "hygienic copy paste" would simply
> import the beginner prelude qualified and mangle identifiers as necessary.
>
> I'm inclined to think the Racket way is the only true solution here.
>
> John
>
>
> On Wed, Feb 24, 2016 at 6:07 PM, Manuel M T Chakravarty <
> chak at justtesting.org> wrote:
>
>> Two notable differences between Racket and the situation in Haskell is
>> that (1) Racket has a full blown IDE to support the staged languages and
>> (2) AFIK any Racket program in a simpler language is still a valid Racket
>> program in a more advanced language. (The latter wouldn’t be the case with,
>> e.g., a Prelude omitting type classes as you need to introduce new names
>> —to avoid overloading— that are no longer valid in the full Prelude.)
>>
>> Manuel
>>
>> > Eric Seidel <eric at seidel.io>:
>> >
>> > On Wed, Feb 17, 2016, at 08:09, Christopher Allen wrote:
>> >> I have tried a beginner's Prelude with people. I don't have a lot of
>> data
>> >> because it was clearly a failure early on so I bailed them out into the
>> >> usual thing. It's just not worth it and it deprives them of the
>> >> preparedness to go write real Haskell code. That's not something I'm
>> >> willing to give up just so I can teach _less_.
>> >
>> > Chris, have you written about your experiences teaching with a
>> > beginner's Prelude? I'd be quite interested to read about it, as (1) it
>> > seems like a natural thing to do and (2) the Racket folks seem to have
>> > had good success with their staged teaching languages.
>> >
>> > In particular, I'm curious if your experience is in the context of
>> > teaching people with no experience programming at all, vs programming
>> > experience but no Haskell (or generally FP) experience. The Racket "How
>> > to Design Programs" curriculum seems very much geared towards absolute
>> > beginners, and that could be a relevant distinction.
>> >
>> > Thanks!
>> > Eric
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