flickr.js

// _ is an instance of Ramda
// $ is an instance of jQuery

// This is an app extracted from the book
// mostly-adequate-guide/content/ch6.html

// it's query the flickr API's and mount 
// a lots of images on the page

// IMPURE functions ahead 

// takes a function (callback) and returns another 
// function which takes an url
var getJSON = _.curry(function(callback, url) {
  $.getJSON(url, callback);
})

// takes a selector and returns a functions
// which you can pass an html
var setHtml = _.curry(function(sel, html) {
  $(sel).html(html);
})

// PURE, good and reliable functions ahead

// just create an image for a given url
var img = function(url) {
  return $('<img />', {
    src: url,
  });
};

// just create an url for a given query
var url = function(t) {
  return 'http://api.flickr.com/services/feeds/photos_public.gne?tags=' +
    t + '&format=json&jsoncallback=?';
};

// _.prop is a curried function which takes 
// a property name and then an object
// ex:   var getPrice = _.prop('price')
//       getPrice({price: 3, x: "y"}) // returns 3

// takes an object extracts its media and
// then from the media it extracts the m property
var mediaUrl = _.compose(_.prop('m'), _.prop('media'));

// it takes a media url and create an image
var mediaToImg = _.compose(img, mediaUrl);

//it takes an object and extracts items from it
// map each one to an image
var images = _.compose(_.map(mediaToImg), _.prop('items'));

// it takes images and set
// them on the document.body
var renderImages = _.compose(setHtml('body'), images);

// given a string, it'll create an url and 
// gets the json and render the images
var app = _.compose(getJSON(renderImages), url);

// given a query it'll create a page
app('cats');

// I strongly recommend you to read again from app to mediaUrl