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

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  [ 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 fsharp.org. ]

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)

    #r@"....Debugnet45Samples.DataStore.Freebase.dll"

    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

Enjoy!

Don, for The Visual F# Team