How to parse a string literal about browser

[et1975]

The idea of this parser-combinator module is that a single type unifies the parsed out values, what you are asking for can only be represented by a DU, so you need to pass the map function to construct it.

[et1975]

s "blog" in your example refers to a "static" portion - something that is expected to be present in the input, but is not captured, ie the parser as specified has no instructions to extract something and I guess the compiler can't infer the types involved.
parse str "blog" would do what you expect it to do.

[lambdakris]

I was actually looking into how to get something like the following:

type Route = Home | Search of string
let routes = 
    [ map Home (s "home")
      map Search (s "search" </> str) ]
parse (oneOf routes)

or just

parse (map Home (s "home"))

Which works, but I was just hoping there was a way to build a "match a string" expression without applying the map function...