Oct 152009

Pretty Printing in F# interactive

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I’ve started playing around with XML in F# interactive and while F# is a joy to work with, the F# interactive sessions have two rather annoying and easily fixed deficiencies.

  1. XML documents are printed out as a sequence of sequences
  2. Printing out XML as text leaves it unformatted, i.e. the whole document is spread out on a single line

To fix this I put together the following function;

#r "System.Xml"

open System.IO
open System.Xml
open System.Text

fsi.AddPrinter(fun (xml : System.Xml.XmlNode) ->
    use ms = new MemoryStream()
    use w = new XmlTextWriter(ms, Encoding.Unicode)
    w.Formatting <- Formatting.Indented
    xml.WriteContentTo(w)
    w.Flush()
    ms.Flush()
    ms.Position <- int64 0
    use sr = new StreamReader(ms)
    sr.ReadToEnd())

My initial expectation was that there would be a library function for nicely formatting XML. If there is and I haven’t found it, or if anyone knows of a better way to do this, please let me know.

Cheers,

Matt

Posted by Matt Tagged with: ,