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C3 Lang Tiny Essay

created: 16.MAR.2025

I love to learn new programing languages, it help to open the mind to new possibilities and compare different approaches. For instance, I learned Ruby and Scala in 2010, Clojure and Haskell in 2011, Go in 2015, Kotlin 2016, Rust in 2018 and Idris, TypeScript in 2019, 2020 Pandemic strike did a bunch of pocs but not with new langs(crazy year), Zig in 2021, 2022(coding in lots of langs but nothing new) - in 2023 I'm learning Nim and V. Learn at least one lang per year. This post is not complain, it's just to share some toughts, notes and impressions.

Why C3

Created in 2021 by Christoffer Lernö
Evolution not Revolution

Understanding Lean's Foreign Function Interface (FFI)

WARNING

Note on FFI Interface Stability The current Foreign Function Interface (FFI) in Lean 4 was primarily designed for internal use within the Lean compiler and runtime. As such, it should be considered unstable. The interface may undergo significant changes, refinements, and extensions in future versions of Lean. Developers using the FFI should be prepared for potential breaking changes and should closely follow Lean's development and release notes for updates on the FFI system.

How to Read EBNF Grammars?

Reading EBNF grammars is pretty simple:

Enclosed within two ?s is a global capture, it does not mean optional. It means 'I am writing a free-style sentence'.
Enclosed within { and } means : repeat at least zero times
Enclosed within [ and ] means : this is optional
Enclosed within ( and ) means : this is a group

What is the kernel?

The kernel is an implementation of Lean's logic in software; a computer program with the minimum amount of machinery required to construct elements of Lean's logical langauge and check those elements for correctness. The major components are:

A sort of names used for addressing.
A sort of universe levels.
A sort of expressions (lambdas, variables, etc.)

All American Regex

(Credit card # validation regular expression)

The regex \b(?:\d[ -]*?){13,16}\b is a powerful tool used for validating credit card numbers. Credit card numbers typically consist of a sequence of 13 to 16 digits, with optional spaces or dashes in between. This regular expression applies the Luhn algorithm to ensure the validity of credit card numbers by checking for the correct number of digits and the proper formatting. By using this regular expression, developers can easily implement credit card number validation in their applications, helping to enhance security and prevent errors during data entry.

	// This is free and unencumbered software released into the public domain.

	// Anyone is free to copy, modify, publish, use, compile, sell, or
	// distribute this software, either in source code form or as a compiled
	// binary, for any purpose, commercial or non-commercial, and by any
	// means.

	// In jurisdictions that recognize copyright laws, the author or authors
	// of this software dedicate any and all copyright interest in the
	// software to the public domain. We make this dedication for the benefit

	## You need to remove the default dnsmasq package.
	## If you remove straight, it will stop resolving DNS, and that is why we are going to use these following commands
	opkg update; cd /tmp/ && opkg download dnsmasq-full; opkg install ipset libnettle8 libnetfilter-conntrack3;
	opkg remove dnsmasq; opkg install dnsmasq-full --cache /tmp/; rm -f /tmp/dnsmasq-full*.ipk;

	## Install wget if you don't have it.
	## You can skip that if you can upload those files using SCP
	## Check the official repo as those endpoints update frequently therefore change it accordingly
	opkg install wget
	wget https://downloads.sourceforge.net/project/v2raya/openwrt/v2raya.pub -O /etc/opkg/keys/94cc2a834fb0aa03

	DEMZF-UCKEE-HB222-DJDDH-594U5
	DMAZF-UCKEE-A6222-8CADP-HQZ7H
	DPAZF-UCKEE-FH222-ET546-DLRGT
	DRNZF-UCKEE-UK222-RWNLU-XVZH7
	DSBZF-UCKEE-BF222-K24JB-S9JLC
	DSHZF-UCKEE-D3222-NMB93-UKSQF
	DTHZF-UCKEE-BW222-Q2BKZ-NXPU8
	DVAZF-UCKEE-J7222-5UHCT-QSRFE
	DVEZF-UCKEE-PR222-ZAPFE-4C49Q

	Taken from: https://forum.gl-inet.com/t/extroot-configuration/27421
	These were the only commands that seemed to work:

	I used these commands to configure it, it’s working fine so far, just want to check I won’t run into any issues down the line:

	opkg update
	opkg install block-mount kmod-fs-ext4 e2fsprogs

	DEVICE="$(sed -n -e "/\s\/overlay\s.*$/s///p" /etc/mtab)"
	uci -q delete fstab.rwm