I defined the following: import Base: promote_rule struct RationalNumber{T<:Integer} <: Real num::T den::T end #RationalNumber{T}(x::S) where {T<:Integer, S<:Integer} = RationalNumber(x, 1) RationalNumber(n::T, d::T) where {T<:Integer} = RationalNumber{T}(n,d) RationalNumber(n::Integer…

Correct use of promotion and conversion

stevengj March 18, 2024, 1:07am 2

You’re just missing a constructor that makes a RationalNumber from another of a different type:

RationalNumber{T}(r::RationalNumber) where {T} = RationalNumber{T}(r.num, r.den)

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