On Friday, May 27, 2016 at 1:38:36 PM UTC-5, David Kraeutmann wrote:

GHCi enables -XExtendedDefaultRules, which cause read "2" to default to ().

Ah - thank you very much! Indeed it is a consequence of the ExtendedDefaultRules option:

GHCi, version 7.10.2: http://www.haskell.org/ghc/ :? for help

Prelude> :set -XNoExtendedDefaultRules

Prelude> read "2"

<interactive>:3:1:

No instance for (Read a0) arising from a use of ‘it’

On 5/27/2016 8:28 PM, Erik Rantapaa wrote:
> Hi fellow Haskellers!
>
> If I bring up ghci and evaluate `read 2` I get the error "Prelude.read: no
> parse"
>
> GHCi, version 7.10.2: http://www.haskell.org/ghc/ :? for help
> Prelude> read "2"
> *** Exception: Prelude.read: no parse
>
> Exactly how is this message coming about? I understand that `read` needs a
> return type in order to determine which type class instance to run. So, in
> this case, which type is `read` being asked to return?
>
> Thanks,
> Erik
>
>
>
>
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