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A little Clojure configuration reader

This is a handy bit of code I've written more than once. I thought I'd throw it in here so I can refer back to it later. Basically, it lets you read a config file to produce a Clojure map. The config files themselves can contain one or more forms, each of which can be either a map or a list. Maps are simply merged. Lists correspond to invocations of extension points, which in turn produces a map, which is merged along with everything else.

An Example

Consider the following files:

names.edn

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One Hundred Days of Hacking

Objective

Get better at some aspects of creating software by doing them more regularly.

Inspiration

A friend of mine, as a way to "level-up" her young daughter at violin, set a goal that the child would practice every single day for 100 days, without a break. This seems like such a good idea that I decided to steal it.

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;

namespace kchordr
{
    public static class ScanCode 
    {

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(ns com.wangdera.slideshow
  (:use [clojure.contrib.test-is])
  (:import (java.io File)
	   (javax.imageio ImageIO)
	   (javax.swing JFrame JPanel Timer)
	   (java.awt Dimension Frame Color)
	   (java.awt.event ActionListener WindowAdapter)))

(def imagelist (atom []))
(def current-image (atom nil))

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// A Java variation on the same theme

package user;

import java.io.InputStream;
import java.util.Random;

public class SlowInputStream extends InputStream {
    private final long time;
    private final long size;

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Drawing;
using System.Threading;
using Timer = System.Windows.Forms.Timer;
using System.IO; 

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(defn dopar
  "Given a (potentially infinite) sequence `coll`, uses core.async to
  run `f` for side effects against each value in the collection.
  Performs at most `concur` operations in parallel, and never enqueues
  more than `lead` items ahead of the ones being consumed. If any call
  to `f` throws an exception, it will be rethrown from this function.
  Otherwise, returns nil. Optional timeout value is number of
  milliseconds to wait for all operations to complete."
  ([coll f concur lead] (dopar coll f concur lead nil))
  ([coll f concur lead timeout-ms]

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# Update: This micro-blog is now also a guide on clojurescript.org: 
# http://clojurescript.org/guides/native-executables

# Hello! This is a micro-post about how to produce native executables
# from ClojureScript source. The basic idea is to produce a
# JavaScript file using the ClojureScript compiler, and then use a
# Node.js tool called nexe (https://github.com/jaredallard/nexe) to
# compile that into an executable. The resulting file can be run
# without requiring a node install on the target machine, which can
# be handy.

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Embedding an SSH-accessible REPL in a Clojure process

N.B. This is now a library, thanks to the efforts of the wonderful @mtnygard. And the README does a good job of making clear just how terrible an idea it is to actually do this. :)

As any Clojurist knows, the REPL is an incredibly handy development tool. It can also be useful as a tool for debugging running programs. Of course, this raises the question of how to limit access to the REPL to authorized parties. With the Apache SSHD library, you can embed an SSH server in any JVM process. It takes only a little code to hook this up to a REPL, and to limit access either by public key or

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(require '[clojure.math.combinatorics :as combo]
         '[clojure.core.async :as async])

(def zeus-route
  ["Kadena"
   "Pohang"
   "Pusan"
   "Kimhae"
   "Sachon"
   "Taegu"