public void Part3() {
var person = new Person(
gender: Gender.Male,
age: 59,
clothes: FSharpSet.Create("Jeans"),
sobriety: Sobriety.Paralytic);
var cost = GayBar.CostToEnter(person);
Assert.AreEqual(FSharpChoice.Errors<decimal>("Too old!", "Smarten up!", "Sober up!"), cost);
}
// PERFORM THE CHECKS USING Monadic SUGAR (LINQ)
public static FSharpChoice<decimal, NonEmptyList<string>> CostToEnter(Person p) {
return from a in Club.CheckAge(p)
from b in Club.CheckClothes(a)
from c in Club.CheckSobriety(b)
select c.Gender == Gender.Female ? 0m : 5m;
}
public static FSharpChoice<decimal, NonEmptyList<string>> CostToEnter(Person p) {
return
FSharpList.Create(Club.CheckAge, Club.CheckClothes, Club.CheckSobriety, CheckGender)
.SelectMValidation(check => check(p))
.Select(x => x[0].Age + 1.5m);
}
public void Part2() {
var daveParalytic = new Person(
age: Test1.Dave.Age,
clothes: Test1.Dave.Clothes,
gender: Test1.Dave.Gender,
sobriety: Sobriety.Paralytic);
var costDaveParalytic = ClubTropicana.CostToEnter(daveParalytic);
Assert.AreEqual(FSharpChoice.Errors<decimal>("Too old!", "Sober up!"), costDaveParalytic);
var costRuby = ClubTropicana.CostToEnter2(Test1.Ruby);
Assert.AreEqual(FSharpChoice.Ok(0m), costRuby);
}
public static FSharpChoice<decimal, NonEmptyList<string>> CostToEnter2(Person p) {
return CostByGender.Curry().ReturnValidation()
.ApValidation(Club.CheckAge(p))
.ApValidation(Club.CheckClothes(p))
.ApValidation(Club.CheckSobriety(p));
}
//PERFORM THE CHECKS USING applicative functors, accumulating failure via a monoid
// using LINQ sugar
public static FSharpChoice<decimal, NonEmptyList<string>> CostToEnter(Person p) {
return from c in Club.CheckAge(p)
join x in Club.CheckClothes(p) on 1 equals 1
join y in Club.CheckSobriety(p) on 1 equals 1
select c.Gender == Gender.Female ? 0m : 7.5m;
}
public void Part1() {
var costDave = ClubbedToDeath.CostToEnter(Dave);
Assert.AreEqual(FSharpChoice.Error<decimal>("Too old!"), costDave);
var costKen = ClubbedToDeath.CostToEnter(Ken);
Assert.AreEqual(FSharpChoice.Ok(5m), costKen);
var costRuby = ClubbedToDeath.CostToEnter(Ruby);
Assert.AreEqual(FSharpChoice.Ok(0m), costRuby);
var Ruby17 = new Person(
age: 17,
clothes: Ruby.Clothes,
sobriety: Ruby.Sobriety,
gender: Ruby.Gender);
var costRuby17 = ClubbedToDeath.CostToEnter(Ruby17);
Assert.AreEqual(FSharpChoice.Error<decimal>("Too young!"), costRuby17);
var KenUnconscious = new Person(
age: Ken.Age,
clothes: Ken.Clothes,
gender: Ken.Gender,
sobriety: Sobriety.Unconscious);
var costKenUnconscious = ClubbedToDeath.CostToEnter(KenUnconscious);
Assert.AreEqual(FSharpChoice.Error<decimal>("Sober up!"), costKenUnconscious);
/**
* The thing to note here is how the Validations can be composed together in a computation expression.
* The type system is making sure that failures flow through your computation in a safe manner.
*/
}