The F# 3.0 Freebase Type Provider Sample: Queries for Presidents, Books and Stars


 [ Update: the Freebase type provider is now available as part of the FSharp.Data NuGet package and library. The namespace has changed from “Samples.DataStore.Freebase” to “FSharp.Data”. Find out more about F# at  ]

Part 1 – The Freebase Type Provider Sample – Integrating Internet-Scale Data Sources into a Strongly Typed Language
Part 2 – The Freebase Type Provider Sample – Static Parameters
Part 3 – The Freebase Type Provider Sample – Sample Queries for Presidents,  Books and Stars
Part 4 – The Freebase Type Provider Sample – Some Info On Queries

The F# 3.0 Freebase Type Provider Sample includes some support for query translation from F# 3.0 LINQ queries to MQL.

This means you can write queries in F# 3.0 with auto-completion and strong typing, and still execute efficiently on the server, at least for the queries translated to MQL 

Here are some sample queries using the F# 3.0 Freebase Type Provider Sample.  These are translated fully to MQL (Note: some require the latest updates to the sample)


open Samples.DataStore.Freebase

    let data = Samples.DataStore.Freebase.FreebaseData.GetDataContext()


    // Name some sub-domains of data
let biology = data.Science and Technology.Biology
let computers = data.Science and Technology.Computers
let chemistry = data.Science and Technology.Chemistry
let astronomy = data.Science and Technology.Astronomy
let books = data.Arts and Entertainment.Books


    /// Get the names of the US presidents
let presidents =
query { for e in data.Society.Government.US Presidents do
select e.Name }
|> Seq.toList


    /// Count the stars listed in the database
let numberOfStars = astronomy.Stars.Count()


    /// The name and distances of stars which have a distance recorded.
let someStarDistances =
query { for e in astronomy.Stars do
where e.Distance.HasValue
select (e.Name, e.Distance) }
|> Seq.toList


    /// Get the stars in the database sorted by proximity to earth
let starsSortedByProximityToEarth =
query { for e in astronomy.Stars do
sortBy e.Distance.Value
take 10
select e }
|> Seq.toList


     /// Get some stars close to Earth
let getSomeCloseStars =
query { for e in astronomy.Stars do
where (e.Distance.Value < 4.011384e+18<_>)
select e }
|> Seq.toList


     /// Get the first 10 books matching a user string.
let topBooksWithNameContaining (s:string) =
query { for book in data.Arts and Entertainment.Books.Books do
where (book.Name.ApproximatelyMatches s)
take 10
select book.Name }


    topBooksWithNameContaining “1984” |> Seq.toList


Don, for The Visual F# Team



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