Add info to your field that you will could use to decorate it after

type FormFieldInfo decoration =
    -- the field is mandatory
    FieldIsMandatory
    -- Allow to add custom decoration to field.
    | CustomDecorator decoration (SubComparator decoration)

formFieldComparable

initFormFieldInfos

addFormFieldInfo

removeFormFieldInfo

a function that allow to compare decorator (cf. formFieldComparable) between them. Useful to {add, remove} FormFieldInfo decoration {to,from} field.