Created
November 2, 2024 15:10
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| abstract type Countable{sym} end | |
| Base.show(io::IO, x::Countable{sym}) where sym = print(io, x.n == 1 ? "$sym" : "$(x.n)$sym") | |
| getsym(x::Countable{sym}) where sym = sym | |
| Base.:*(n::Integer, x::Countable) = typeof(x)(n * x.n) | |
| Base.:+(a::Countable, b::Countable) = error("Can't add $(getsym(a))s and $((getsym(b)))s") | |
| Base.:+(a::T, b::T) where {T<:Countable} = T(a.n + b.n) | |
| Base.:<(a::Countable, b::Countable) = error("Can't compare $(getsym(a))s with $(getsym(b))s") | |
| Base.:<(a::T, b::T) where {T<:Countable} = a.n < b.n | |
| struct Fruit{sym} <: Countable{sym} | |
| n::Int | |
| end | |
| struct Animals{sym} <: Countable{sym} | |
| n::Int | |
| end | |
| Base.:+(eaters::Animals, fruit::Fruit) = typeof(fruit)(fruit.n - eaters.n) | |
| const 🍎 = Fruit{:🍎}(1) | |
| const 🍐 = Fruit{:🍐}(1) | |
| const 🍌 = Fruit{:🍌}(1) | |
| const 😮 = Animals{:😮}(1) | |
| const 🐒 = Animals{:🐒}(1) | |
| const 🐄 = Animals{:🐄}(1) | |
| Base.:+(eaters::Animals{:🐒}, fruit::Fruit{:🍌}) = typeof(fruit)(fruit.n - 2 * eaters.n) | |
| function Base.:+(eaters::Animals{:🐄}, fruit::Fruit) | |
| @warn "Moooooo!" | |
| return fruit | |
| end | |
| typeof(🍎) == typeof(🍐) | |
| 🍎 + 2🍎 + 3🍎 | |
| 2🍎 < 3🍎 | |
| 2🍎 + 3🍐 | |
| 🍎 < 🍐 | |
| 4😮 + 6🍎 | |
| 2😮 + 6🍌 | |
| 2🐒 + 6🍌 | |
| 2🐄 + 6🍌 |
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