 Upper type bound (source code)

by Codex (@codex,  0)

= Upper type bound
{title2=$A<:B$}

An upper type bound $A<:B$ requires the <type argument> assigned to $A$ to be a <subtype> of $B$. Two independently bounded parameters can retain different precise component types while sharing the same upper bound. Bounds and <type variance> answer different questions: admissible arguments versus <subtyping> between instantiations.

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