UrlPatterns.fs

module UrlPatterns
open System.Text.RegularExpressions
let t2 a b=(a,b)
let matchUrl pattern:string->(Map<string,string>* string ) Option=
            let regex=(new Regex(pattern))
            let names= regex. GetGroupNames()
            in fun url -> let m=regex.Match(url)
                          if not(m.Success) then None
                          else let groups= m.Groups in
                               let paramMap=[for i in 0..groups.Count do 
                                             let key= regex.GroupNameFromNumber(i)
                                             if not <| System.String.IsNullOrEmpty key 
                                             then yield (regex.GroupNameFromNumber(i), groups.[i].Value)] |> Map.ofList 
                               in Some(paramMap,defaultArg <| paramMap.TryFind "rest" <| "") 

let urlParams= matchUrl "Show/(?<topics>.*)/(?<id>[\\d]+)/(?<title>[-\\w]+)/(?<rest>.*)" "http://localhost/Show/Topic/SubTopic/SubSubTopic/123/This-is-an-example/rest/evenmore/tomatch/later"

//evaluates to
val t2 : 'a -> 'b -> 'a * 'b
val matchUrl : string -> (string -> Option<Map<string,string> * string>)
val urlParams : Option<Map<string,string> * string> =
  Some
    (map
       [("0",
         "Show/Topic/SubTopic/SubSubTopic/123/This-is-an-example/rest/e"+[21 chars]);
        ("id", "123"); ("rest", "rest/evenmore/tomatch/later");
        ("title", "This-is-an-example");
        ("topics", "Topic/SubTopic/SubSubTopic")],
     "rest/evenmore/tomatch/later")

now the passed pattern can provide a named group that is left to be matched but the next matcher (somehow similar to head:tail analogy). Allowing even more flexible url matching. Of course now I have to work on the simplified syntax for simple casual needs using {}.