Functional JavaScript Notes

Functional JavaScriptDirectory

• 1 Get Started with FP
• 2 first-class Functions and applicative programming
• 3 Variable Scope and Closures
• 4 High-order Functions
• 5 function-building Functions
• 6 recursion
• 7 Purity, immutability and policies for change
• 8 flow-based Programming
• 9 Programming without Class
• Ten Appendix

Get Started with FP

1. CSV Parse:

   return _.reduce (str.split ("\ n"), function (table, row) {
   Table.push (_.map (Row.split (","), function (cell) {return Cell.trim ();})); return table;}, []); };

2. The author is the author of Clojurescript?

first-class Functions and applicative programming

1. Return _.reduceright (arguments, function (truth,f) {return truth && f ();}, True);
2. Pass NULL as the first argument to apply: This means that this refers to the global object ...
3. P44 Traditional SQL Select actually corresponds to project in the relational algebra
4. JS's lambda syntax is too cumbersome to write FP-style code that brings trouble
   1. Restrict (Project (as (library, {ed: ' Edition '), [' Title ', ' ISBN ', ' edition ']),
      function (book) {return book.edition>1;});

Variable Scope and ClosuresHigh-order Functionsfunction-building Functions

1. function partial (fun/*, Pargs */) {
   var pargs = _.rest (arguments);
   return function (/* arguments */) {
   var args = Cat (Pargs, _.toarray (arguments));
   Return fun.apply (fun, args);
   } }

recursion

1. Trampoline (Avoid mutual-recursive overflow):
   1. function even (n) {if (n==0) return true; else return Partial1 (odd , n-1); }
      1. ==> odd (20000001) () () ... ();
   2. Function Trampoline (fun/*, args */) {
      var result = fun. Apply (fun, _.rest (arguments)); Here we go.
      while (_.isfunction (result)) result = result ();
      return result; }
2. generator (lazy infinite sequence)
   1. head-tail () abstraction, where tail encapsulates the calculation of the remaining series
   2. function Gentake (n, Gen) {
      var dotake = function (x, g, ret) {if (x==0) return ret; else return partial ( Dotake, X-1, Gentail (g), Cat (ret, Genhead (g)));
      return trampoline (Dotake, N, Gen, []);

Purity, immutability and policies for change

1. Object#freeze = Deepfreeze
2. API: Let object modification method return new Object instance

flow-based Programming

1. _.chain
2. Lazychain
   1. thunk:a function waiting to be called
   2. #force ()
3. JQuery $. Deferred ()
4. Pipelining
5. Action (Monad): Flowing in context?
   1. Lift
   2. Actions

Programming without Class

1. Mixins
   1. var polytostring = dispatch (function (s) {return _.isstring (s)? s:undefined;}, ...
2. var mymixin = {
   Setvalue:function (v) {... this._value = v; this.notify (Oldval, v);}
3. _.extend (Myclass.prototype, mymixin);
4. var CAS = function (val) {Myclass.call (this, Val);}
   1. var casmixin = ...

Appendix

1. Underscore-contrib
2. RxJS
3. Bilby ' s Multimethods
4. Allong.es:support for stateful iterators
5. *reducers:inspired by Clojure ' s reducer
6. Clojurescript (the author wrote "The Joy of Clojure"?) ）
7. Coffeescript
   1. Literate programming
   2. Varargs
   3. List understanding
   4. Deconstruction Assignment
8. Roy:inspired by ML
9. ELM (+ + + not required for string stitching): FRP

Functional JavaScript Notes