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# cat extlinux.conf 
# Generated file, all changes will be lost on nixos-rebuild!

# Change this to e.g. nixos-42 to temporarily boot to an older configuration.
DEFAULT nixos-default

MENU TITLE ------------------------------------------------------------
TIMEOUT 50

LABEL nixos-default

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# Sample variables file for BCM94356Z NGFF 22x30mm iPA, iLNA board with PCIe for production package
NVRAMRev=$Rev: 492104 $
#4356 chip = 4354 A2 chip
sromrev=11
boardrev=0x1102
boardtype=0x073e
boardflags=0x02400201
#0x2000 enable 2G spur WAR
boardflags2=0x00802000
boardflags3=0x0000000a

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[    0.000000] Booting Linux on
 physical CPU 0x0000000000 [0x410fd034]
[    0.000000] Linux version 5.4.89 (nixbld@localhost) (gcc version 9.3.0 (GCC)) #1-NixOS SMP Tue Jan 12 19:16:25 UTC 2021
[    0.000000] Machine model: FriendlyElec NanoPC-T4
[    0.000000] efi: Getting EFI parameters from FDT:
[    0.000000] efi: UEFI not found.
[    0.000000] cma: Reserved 32 MiB at 0x00000000f6000000
[    0.000000] NUMA: No NUMA configuration found
[    0.000000] NUMA: Faking a node at [mem 0x0000000000200000-0x00000000f7ffffff]
[    0.000000] NUMA: NODE_DATA [mem 0xf57ef800-0xf57f0fff]

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[    0.000000] Booting Linux on physical CPU 0x0000000000 [0x410fd034]
[    0.000000] Linux version 5.4.89 (nixbld@localhost) (gcc version 9.3.0 (GCC)) #1-NixOS SMP Tue Jan 12 19:16:25 UTC 2021
[    0.000000] Machine model: FriendlyElec NanoPC-T4
[    0.000000] efi: Getting EFI parameters from FDT:
[    0.000000] efi: UEFI not found.
[    0.000000] cma: Reserved 32 MiB at 0x00000000f6000000
[    0.000000] NUMA: No NUMA configuration found
[    0.000000] NUMA: Faking a node at [mem 0x0000000000200000-0x00000000f7ffffff]
[    0.000000] NUMA: NODE_DATA [mem 0xf57ef800-0xf57f0fff]
[    0.000000] Zone ranges:

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package main

import (
	"fmt"
)

func fibonacci(n uint) uint64 {
	if n <= 1 {
		return uint64(n)
	}

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tmux Cheat Sheet

Table of Contents

• General Usage
• Shortcuts
• Commands
• Scripting tmux
• Configuring tmux

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mysql> describe account;
+----------+------------------+------+-----+-------------------+-------------------+
| Field    | Type             | Null | Key | Default           | Extra             |
+----------+------------------+------+-----+-------------------+-------------------+
| id       | int(10) unsigned | NO   | PRI | NULL              | auto_increment    |
| username | varchar(255)     | NO   |     | NULL              |                   |
| ts       | timestamp        | YES  |     | CURRENT_TIMESTAMP | DEFAULT_GENERATED |
+----------+------------------+------+-----+-------------------+-------------------+
3 rows in set (0.01 sec)

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Travis-Whitton's-MacBook-Pro:nix traviswhitton$ cat node.nix
# This imports the nix package collection,
# so we can access the `pkgs` and `stdenv` variables
with import <nixpkgs> {};

# Make a new "derivation" that represents our shell
stdenv.mkDerivation {
  name = "my-environment";

  # The packages in the `buildInputs` list will be added to the PATH in our shell

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#!/usr/bin/ruby
fh = File.new('names.csv', 'r')

names = []
while line = fh.gets
  line.chomp!
  names << line
end

names = names.shuffle

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Scalable program architectures
Haskell design patterns differ from mainstream design patterns in one important way:

Conventional architecture: Combine a several components together of type A to generate a "network" or "topology" of type B

Haskell architecture: Combine several components together of type A to generate a new component of the same type A, indistinguishable in character from its substituent parts

This distinction affects how the two architectural styles evolve as code bases grow.

The conventional architecture requires layering abstraction on top of abstraction: