In GHCi, we can bind an IO result into a name with <-.

> a <- return "hello" :: IO String
> a
"hello"
> :t a
a :: String

In PSCi, we can surely use unsafePerformEff, but I think it may be handy to support <- too.

> let eff = pure "hello" :: forall e. Eff e String
> let a = unsafePerformEff eff
> b <- eff

I'm thinking about implementing this, but first I'd like to hear some ideas about this.