reedho notes

Given that your clojure environment already setup correctly, this flow demonstrated how to quickly exploring libraries:

lein try com.cemerick/pomegranate

Then on the repl:

(require 'cemerick.pomegranate) (defn add-deps! [dv] (cemerick.pomegranate/add-dependencies :coordinates dv :repositories (merge cemerick.pomegranate.aether/maven-central {"clojars" "http://clojars.org/repo"})))

Say i want to explore ring, then:

(add-deps! '[[ring/ring-core "1.4.0"]]) (require 'ring.util.io) (ring.util.io/last-modified-date (java.io.File. "/"))

Doing xhr on your (latest chrome) browser dev console, as easy as:

var __xhr = new XMLHttpRequest; __xhr.onreadystatechange = (e) => console.log("rsc:", e) __xhr.open("GET", "/somepath") __xhr.send()

Given your ns declaration is like this:

(ns piko.core (:require [piko.route :as r]))

Then

::r/payment

Dooh, may the form below help you memories on string, stream and reader!

Oi, hola Bang Jeff.

Boljug neh, ntar gue telp ye agak maleman, di kantor gak dapet sinyal ^^.

Below snippets demonstrate the usages of core.async/ into and map:

Put 100 values to channel with buffer size of 10 and read whats in the channel after. Note that reading the LinkedList of the channel directly by .buf give you NO guarantee on multithreading aspects:

Scope that i want to talk here is about scope of an identifier in a programming language.

Suppose a scenario like this, in the exact order:

define a global variable x and bound 1 to it. Here x is the so called identifier.

define a function F which print the x variable above.

define another function G which does 2 things: (1) define a local variable with same name x and bound 100 to it, and (2) call function F above.

call the function G.

Guess what will be printed out by function F in the call of G?

Okay, let first make it with Clojure:

(def x 1) (defn F [] (prn x)) (defn G [] (let [x 100] (F)))

Pretty stright forward, yes! its also beautiful. Now lets see what the result of calling function G:

(G) ;; 1

Ok, seems logical. Lets now try it with the famous Javascript, try this with Google Chrome console (open new tab then C-I --or Ctrl-Shift-I, then clik Console tab in the inspector menu bar).

var x = 1 function F() { console.log(x); } function G() { var x = 100; F(); } G(); // 1

Oh, sure, same old, same result.

Do all programming will behave the same? Lets try once with some others:

Ruby:

$x = 1 def _F_ puts $x end def _G_ x = 100 _F_ end _G_ # 1

Perl:

$x = 1; sub F { print $x, "\n" } sub G { my $x = 100; F; } G; # 1

Wow.. its turn out that Ruby and Perl also does the same thing. So, now i can say most of languages use this kind of execution strategy. This is the one that is called as Lexical scoping, also known as Static scope in contrast to the other strategy that is called Dynamic scope.

Lets looks a language with dynamic scope nature. Wikipedia's page of Scope said that Bash (the bourne again shell) is one of them. Here is a bash script of it:

File /tmp/t.sh:

#!/usr/bin/env bash x=1 function F() { echo $x; } function G() { local x=100; F; } G;

Executing the script yield 100. Yes, its show 100, NOT 1.

chmod a+x /tmp/t.sh /tmp/t.sh

Other language which is historically use Dynamic scoping nature is the original Lisp and early Lisp dialects. Famous one that still use Dynamic scoping is Emacs Lisp (aka elisp). Here are the elisp version:

(setq x 1) (defun F () (message "%s" x)) (defun G () (setq x 100) (F)) (G)

Do M-x eval-region or such, will show 100.

Some language also can do both, e.g. Perl, Common Lisp and Clojure. Here are the version of Perl and Clojure that make use of Dynamic scoping:

Perl:

$x = 1; sub F { print $x, "\n" } sub G { local $x = 100; F; } G; ## 100

In this version, it use local instead of my to have Dynamic scope semantic.

Clojure:

(def ^:dynamic x 1) (defn F [] (prn x)) (defn G [] (binding [x 100] (F))) (G) ;; 100