Single-file executable literate Haskell with Stack

README.lhs

#!/usr/bin/env stack
> -- stack --resolver lts-6 --install-ghc runghc --package classy-prelude --package lens --package wreq

Blah Blah words about this single file executable README goes here.

> {-# LANGUAGE DeriveAnyClass #-}
> {-# LANGUAGE DeriveGeneric #-}
> {-# LANGUAGE NoImplicitPrelude #-}
> {-# LANGUAGE OverloadedStrings #-}

explain explain

> import ClassyPrelude
> import Control.Lens
> import Network.Wreq
> import Data.Aeson

more explaining

> data IPInfo = IPInfo
>     { ip :: Text
>     , hostname :: Text
>     , city :: Text
>     , region :: Text
>     , country :: Text
>     , loc :: Text
>     , org :: Text
>     , postal :: Text
>     } deriving (Show,Generic,ToJSON,FromJSON)

you are probably confused right now. let me explain

> main = do
>   let opts = defaults & header "User-Agent" .~ ["curl/7.47.0"]
>   eInfo <- eitherDecode . view responseBody <$> getWith opts "http://ipinfo.io"
>   either print (putStrLn . city) (eInfo :: Either String IPInfo)

when I run it like this:

user@computer:~/src% ./README.lhs 
Portland

you can see that I'm in Portland