I have been working with the regular expression package (Text.Regex.Posix). My hope was to find a simple way to remove a pair of XML tags from a short string. I have something like this "<tag>Data</tag>" and would like to extract 'Data'. There is only one tag pair, no nesting, and I know exactly what the tag is. My first attempt was this: "<tag>123</tag>" =~ "[^<tag>].+[^</tag>]"::String result: "123" Upon further experimenting I realized that it only works with more than 2 digits in 'Data'. I occured to me that my thinking on how this regular expression works was not correct - but I don't understand why it works at all for 3 or more digits. Can anyone help me understand this result and perhaps suggest another strategy? Thank you.