Polymorphic `if` statement

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two possible solutions:

First: type alias

type ShouldShow = Bool

I guess it’s self explanatory. Of course it allows the use of if and so on. The way you named the type, ShouldShow, there is no confusion what True and False represent and you are about to reimplement Bool, anyway.

Second: don’t use if

This is how I actually do stuff:

data ShowHide
  = Show
  | Hide

More verbose and explicit alternative:

data Visibility
  = VisibilityShow
  | VisibilityHide

Of course, both of them allow to add a third value at any time, e.g. for a blocking and a collapsing version of a hidden state.

And I don’t usually see a problem with the resulting

case visibility of
  VisibilityShow -> ...
  VisibilityHide -> ...

My personal choice

My dirty secret: I even use case on bool types because if results in line breaks and white space that interrupt the flow (my subjective view). case is just so much clearer and more flexible at the same time.

Because of my dirty secret your initial problem/challenge turns out to be none. Avoid boolean blindness, prefer case over if strictly, have elegant and flexible code.

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