F# Quotation Generating very strange compile error

Question

I am trying to work out why the following line:

let emailQuotation: Expr<LoginView -> string> = <@ fun (v: LoginView) -> v.Email.Text @>

is failing with a compile error, saying "Lookup of object on indeterminate type...". The property ViewModel.Email is a Xamarin Forms Entry, containing a Text property.

What more information does the compiler need, and why is it not able to interpret this expression?

score 1 · Answer 1 · answered Aug 01 '16 at 17:47

1

My solution is ugly. I can do this:

let emailQuotation = <@ fun (v: LoginView) -> let email: Entry = v.Email in email.Text @>

The quotation wasn't able to interpret the type of v.Email. I'm no expert on code quotations, so there may be a way to make the compiler pick up the type in a single expression.

answered Aug 01 '16 at 17:47

Rob Lyndon

12,089
5
49
74

Would this work? `fun (v: LoginView) -> (v.Email:Entry).Text` – Joel Mueller Aug 02 '16 at 23:25
I'll try. If it does work, feel free to submit an answer and I'll upvote it and mark it as the answer. – Rob Lyndon Aug 02 '16 at 23:28
It works nicely. If you submit this as an answer, I'll mark it accordingly. – Rob Lyndon Aug 02 '16 at 23:40

F# Quotation Generating very strange compile error

1 Answers1