style: use consistent operators in De Morgan's Law

[jechol]

Update De Morgan's Law to use basic operators (not, and, or) instead of nand/nor:

• NOT (A AND B) = (NOT A) OR (NOT B)
• NOT (A OR B) = (NOT A) AND (NOT B)

This matches the moduledoc and other rewrite rules which only use basic operators.

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Leave anything that you believe does not apply unchecked.

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[maennchen]

@jechol Those compile to exactly the same code:

crux/lib/crux/expression.ex

Lines 160 to 191 in 0fb4a4f

	{:nand, _, [left, right]} ->
	quote do
	{:not, {:and, unquote(left), unquote(right)}}
	end
	{:nor, _, [left, right]} ->
	quote do
	{:not, {:or, unquote(left), unquote(right)}}
	end
	{:xor, _, [left, right]} ->
	quote do
	{:and, {:or, unquote(left), unquote(right)},
	{:not, {:and, unquote(left), unquote(right)}}}
	end
	{:xnor, _, [left, right]} ->
	quote do
	{:not,
	{:and, {:or, unquote(left), unquote(right)},
	{:not, {:and, unquote(left), unquote(right)}}}}
	end
	{:implies, _, [left, right]} ->
	quote do
	{:not, {:and, unquote(left), {:not, unquote(right)}}}
	end
	{:implied_by, _, [left, right]} ->
	quote do
	{:not, {:and, unquote(right), {:not, unquote(left)}}}
	end

I thought that the higher level nand / nor might be easier to understand when reading the code. Not sure though if that is correct.

[jechol]

I get that they compile to the same code. I wanted to match the moduledoc though – it uses basic operators, so I figured the implementation should be consistent with that. Fair point though, nand/nor works fine. Let's just close this.