[Haskell-cafe] [] == []

[Rustom Mody]

On Tue, Mar 10, 2015 at 8:07 AM, Lyndon Maydwell <maydwell at gmail.com> wrote:

> This looks like a great opportunity to try out the new holes functionality:
>
> [Prelude] λ [] == _what
>
> <interactive>:3:7:
>     Found hole ‘_what’ with type: [t0]
>     Where: ‘t0’ is an ambiguous type variable
>     Relevant bindings include it :: Bool (bound at <interactive>:3:1)
>     In the second argument of ‘(==)’, namely ‘_what’
>     In the expression: [] == _what
>     In an equation for ‘it’: it = [] == _what
>
>
> Looks like it defaults to [Bool]!
>
> Correct me if I'm wrong :)
>

Thanks Lyndon.
But on my (debian testing) ghc I get:

Prelude> [] == _what

<interactive>:2:7: Not in scope: `_what'

[ghc 7.6.3]

And my main question is the second one :
For pedagogic purposes I want to get the error -- Whats the (family of)
related options?
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