Why does the Age type look as it does?

[ploeh]

The module Shared.Types.Patient contains this definition:

type Age =
    {
        Years: int<year>
        Months: int<month>
        Weeks: int<week>
        Days: int<day>
    }

I'm trying to understand why it looks like this. My current guess is that it's intended to address some user-interface concern, or perhaps model how clinicians normally work with patient ages.

Even so, this seems unwarranted. The only references to the Years, Months, Weeks, or Days properties that I can find outside of Shared.Model are two examples in App.

The first one looks like this:

let age = Patient.Age.fromBirthDate DateTime.Now (DateTime(year, month, day))

let patient =
    Patient.create
        (Some age.Years)
        (Some age.Months)
        (Some age.Weeks)
        (Some age.Days)
        weight
        height
        gaWeeks
        gaDays
        UnknownGender
        [
            if cvl then
                CVL
        ]
        None
        dep

The second is similar:

let age = Patient.Age.fromDays days

let patient =
    Patient.create
        (Some age.Years)
        (Some age.Months)
        (Some age.Weeks)
        (Some age.Days)
        weight
        height
        gaWeeks
        gaDays
        UnknownGender
        cvl
        None
        dep

This seems like an overly complicated way to store what could just as well have been an integer measuring total days.

Am I missing something?

[ploeh]

Oh, I completely forgot, related to yesterday's brief mention of the 'pits of success': One of the things we like to do with algebraic data types is to make illegal states unrepresentable. The current definition of Age, however, doesn't seem to offer anything in terms of encapsulation:

> let a = { Years = -1<year>; Months = 13<month>; Weeks = 7<week>; Days = 1337<day> };;
val a: Age = { Years = -1
               Months = 13
               Weeks = 7
               Days = 1337 }

[halcwb]

@ploeh That's the part of the code base that really needs some quality improvement. GenPRES is a merge between what was originally intended an emergency list app that was client side only. Patient and related concepts are particularly tricky as there are now multiple libraries dealing with different views on what a patient is.

So, you are. not missing anything.

[ploeh]

[...] Patient and related concepts are particularly tricky as there are now multiple libraries dealing with different views on what a patient is.

Yes, I've noticed 😀

I take it that you are open to pull requests suggesting improvements and simplifications.