Pipelining functions with different parameters in F# - f#

Question

I have the following code:
type CustomerStatus = |Valid |Invalid
type Customer = {Id:int; FirstName: string; LastName:string; Status: CustomerStatus}
let checkCustomerFirstName (customers: Customer seq) =
customers
let checkCustomerLastName (customers: Customer seq) =
customers
let checkCustomerInBlockedList (customers: Customer seq) (blockedList: string seq) =
customers
The Customer record type has 4 attributes: Id, FirstName, LastName, and Status. CustomerStatus is defined in the line above as a DU with Valid and Invalid. I then have three functions to validate a sequence of customers, I omitted the function body for the sake of brevity. Notice the 3rd function takes in a second parameter - a list of strings that the customer's name is compared to see if they are invalid.
Here is some test data:
let customers =
[
{Id=0;LastName="Customer0";FirstName="Test";CustomerClass=Valid}
{Id=1;LastName="Customer1";FirstName="Test";CustomerClass=Valid}
{Id=2;LastName="Customer2";FirstName="Test";CustomerClass=Valid}
{Id=3;LastName="Customer3";FirstName="Test";CustomerClass=Valid}
{Id=4;LastName="Customer4";FirstName="Test";CustomerClass=Valid}
]
let blockedList = ["Customer3"]
When I pipeline the first two functions like this:
customers
|> checkCustomerFirstName
|> checkCustomerLastName
Everything works as expected.
However, when I add in the 3rd function,
customers
|> checkCustomerFirstName
|> checkCustomerLastName
|> checkCustomerInBlockedList blockedList
I get a error like this
How do I pipeline functions that have additional parameters?

Answer 1

You can try changing the order of your last method parameters.
let checkCustomerInBlockedList (blockedList: string seq) (customers: Customer seq) =
customers
Forward pipe operator sends the parameter that you have on left side to the function on the right side. In case of your last call you have or the left side a sequence of Customers, but on right side you have a method with parameter, so your sequence will be fed as last parameter.
Your last statement looks like checkCustomerInBlockedList blockedList customers that's why changing the order of parameters will make compiler happy.