Decided to take the Twitter search (http://byteonmyside.wordpress.com/2013/05/17/a-twitter-search-client-in-10-lines-of-code-with-f-and-the-json-type-provider/) and roughly calculate Twitter's attitude to a topic. Very rough approximation of attitude but it gave me a chance to try some more F# stuff. Some changes which I know I can make next: ty…

Program.fs

open System.Linq
type T = FSharp.Data.JsonProvider<"http://search.twitter.com/search.json?q=%23fsharp&lang=en&rpp=1&page=1">
let positives = [| "good"; "awesome"; "sweet"; "nice"; "cool" |]
let negatives = [| "crap"; "terrible"; "poor"; "bad"; "awful" |]

let tweets (tag:string) (since: System.DateTime) = 
    let enc = System.Net.WebUtility.UrlEncode : string -> string
    let rec page n =
        if n < 16 then
            let data = T.Load(sprintf "http://search.twitter.com/search.json?q=%s&rpp=100&page=%d&since=%4d-%02d-%02d" (enc tag) n since.Year since.Month since.Day)
            seq{
                yield! data.Results
                if not (Seq.isEmpty data.Results) then yield! page (n+1)
            }
        else
            Seq.empty
    page 1

let rec positiveString (str:string list) = 
    match str with
        | [] -> false
        | head::tail -> (if positives.Contains(head) then
                            true
                         else positiveString tail)

let (|PositiveTweet|_|) (tweet:string) = 
    let lowerString = tweet.ToLower().Split(' ')
                        |> Array.toList
    let result = positiveString lowerString
    match result with
        | true -> Some ()
        | false -> None

let rec negativeString (str:string list) = 
    match str with
        | [] -> false
        | head :: tail -> (if negatives.Contains(head) then
                                true
                           else
                                negativeString tail)

let (|NegativeTweet|_|) (tweet:string) = 
    let lowerString = tweet.ToLower().Split(' ')
                        |> Array.toList
    let result = negativeString lowerString
    match result with
        | true -> Some ()
        | false -> None

[<EntryPoint>]
let main argv = 
    let searchTerm = Array.get argv 0
    let posCount, negCount, indifferentCount = ref 0, ref 0, ref 0
    tweets searchTerm (System.DateTime.UtcNow - new System.TimeSpan(5,0,0,0))
        |> Seq.iter (fun t ->
                        match t.Text with
                            | PositiveTweet tweet -> posCount := !posCount + 1
                            | NegativeTweet tweet -> negCount := !negCount + 1
                            | _ -> indifferentCount := !indifferentCount + 1 )
    let basicPosPercentage:float = ((float !posCount) / ((float !posCount) + (float !negCount))) * 100.0
    printfn "Found %d positive tweets and %d negative tweets\n" !posCount !negCount
    printfn "Twitter is %f%% positive about %s" basicPosPercentage searchTerm

    System.Console.ReadLine()
        |> ignore
    0