Back to Questions
1.7k
views3
comments
_ Syntax for quotation templates is not working for me
f#templates

In F# for VS 2008 version 1.9.6.16 when trying to do the following (contrived example)
let items = [|5; 4; 6 |]
let x = <@ {for item in items do yield _} @> 5
I get error FS0010: Unexpected symbol '_' in expression.

Please note that I know I can do the following
let items = [|5; 4; 6 |]

let value = 5

let x = <@ {for item in items do yield %value} @>
but this will not work for my actual case. I also tried the samples from [link:tomasp.net] where the "hole" is being used and got the same issue.

Does anyone know why this is not working or another way to accomplish what I am trying to do?

BTW: What I am trying to do is to pass an expression to a function which fills the hole.

.

but this will not work for my actual case.

Why not? The old hole syntax

1

<@ ... _ ... @>

is equivalent to

1

fun x -> <@ ... %x ... @>

so it should always be replaceable.

By on 7/10/2009 3:07 AM ()

Fair point! Thanks for the question back. I was not thinking functionally enough about the problem. What I was trying to do was build a LinqToSQL query that I would not have to copy and paste in a bunch of different places to get data from my constant table.(I wanted to also memoize the computations so I don't have to hit the DB for constant data that stays the same through the life of the app).

By on 7/10/2009 6:42 AM ()

Also, I should add is the _ deprecated as it does not seem to work in the latest version?

By on 7/10/2009 6:43 AM ()

    Topic tags

    IntelliFactory Offices Copyright (c) 2011-2012 IntelliFactory. All rights reserved.
    Home | Products | Consulting | Trainings | Blogs | Jobs | Contact Us | Terms of Use | Privacy Policy | Cookie Policy     		Built with WebSharper