id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc,os,architecture,failure,difficulty,testcase,blockedby,blocking,related
4832,Inconsistent import of instances in GHCi,sebf,,"Issuing `import M` in GHCi does not bring the same instances into scope as issuing `:m + M` and loading a file that contains `import M` do.

For example, the module `Control.Applicative` imports `Control.Monad.Instances` which defines a `Functor` instance for `((->) r)`. The following GHCi session demonstrates that this instance is not in scope after issuing an `import` command in GHCi but it is in scope after issuing an `:m +` command. It is also in scope after loading a file that imports `Control.Applicative`.

{{{
Prelude> fmap id id ()

<interactive>:1:1:
    No instance for (Functor ((->) ()))
      arising from a use of `fmap'
    Possible fix: add an instance declaration for (Functor ((->) ()))
    In the expression: fmap id id ()
    In an equation for `it': it = fmap id id ()
Prelude> import Control.Applicative
Prelude Control.Applicative> fmap id id ()

<interactive>:1:1:
    No instance for (Functor ((->) ()))
      arising from a use of `fmap'
    Possible fix: add an instance declaration for (Functor ((->) ()))
    In the expression: fmap id id ()
    In an equation for `it': it = fmap id id ()
Prelude Control.Applicative> :m + Control.Applicative
Prelude Control.Applicative> fmap id id ()
()
}}}

I expected that issuing an `import` command in GHCi has the same effect as issuing an `:m +` command or loading a file with an `import` statement.",bug,closed,high,7.4.1,GHCi,7.0.1,fixed,,,Unknown/Multiple,Unknown/Multiple,None/Unknown,,,,,