peel-off the only present effect
peel-off the only present effect
An Eff[R, A] value can be transformed into an Eff[U, A] value provided that all the effects in R are also in U
An Eff[R, A] value can be transformed into an Eff[U, A] value provided that all the effects in R are also in U
base runner for an Eff value having no effects at all
base runner for an Eff value having no effects at all
This runner can only return the value in Pure because it doesn't known how to interpret the effects in Impure