Just -package:rebase

Runs a Maybe generator until it produces a Just. This is implemented using filter and has the same caveats.

Analogous to Just and equivalent to return

Analogous to Just, promotes a value of type typ into one of type Maybe typ. It should hold that val . Just === just . val. This function will try not to produce a nested Maybe. This is in accord with how SQL represents NULL. That means that just . just = just. This behavior was changed in v3.6.0.0. If you want to produce nested Maybe, see just'.

A prism on the Just element of a Maybe.

just :: Prism (Maybe a) (Maybe b) a b

A prism on the Just element of a Maybe.

Cast record phantom type into Maybe.

Cast into Maybe on record phantom type.

Assert that some value is Just.

A predicate checking if the input is Just, wrapping a value matching the given predicate.

>>> Just 1 `shouldSatisfy` P.just (P.gt 0)

The Just constructor lifted over the Expr type. This works for the Bool, Int, Char argument types and their lists.

> just zero
Just 0 :: Maybe Int
> just false
Just False :: Maybe Bool

A Predicate that accepts Maybe values of Just x, where x matches the given child Predicate.

>>> accept (just (eq "value")) Nothing
False

>>> accept (just (eq "value")) (Just "value")
True

>>> accept (just (eq "value")) (Just "wrong value")
False

Cast record phantom type into Maybe.

TMap which contains only one entry from the empty string to a.

Justification for label and maybe other widgets (text?)