elm-purl

A tiny library for building parameterized URLs. It is intended to be used with records to give the parameters names and therefore reducing errors.

import Url exposing (Url, (</>), (<?>), (@), root, s, int, bool)

userUrl : Url { id : Int }
userUrl = root </> s "users" </> int .id <?> ("show", bool .show)

userUrl @ { id = 42, show = True } == "/users/42?show=true"

Full API documentation.

Known issues

In Elm precedences for infix operators are applied globally, so if you want to use two packages which define the same operators but with different precedences (eg. this package and evancz/url-parser), you can only use the infix operators of one package freely. Trying to use both packages' operators will lead to compilation problems. This issue contains links to more resources.

A workaround is to use the append etc. functions instead of their infix versions. Here is the above example in this style:

import Url exposing (Url, append, appendParam, root, s, int, bool)

userUrl : Url { id : Int }
userUrl = root 
  |> append (s "users") 
  |> append (int .id)
  |> appendParam "show" (bool .show)

userUrl 
  |> Url.toString { id = 42, show = True } == "/users/42?show=true"

Another workaround is to use explicit parentheses:

userUrl = ((root </> s "users") </> int .id) <?> ("show", bool .show)