Compact Hausdorff reflection ($R:\mathbf{Top}\to \mathbf{KHaus}$)

The inclusion of compact Hausdorff spaces in topological spaces has a left adjoint. Its unit $X\to RX$ is universal among continuous functions from $X$ to compact Hausdorff spaces and has dense image. Completeness follows from products in a category and closed equalizers. For any map $X\to K$, its closed image has a dense subset of cardinality at most $|X|$ and hence cardinality at most $2^{2^{|X|}}$. Representatives of all such compact Hausdorff spaces and maps establish the solution-set condition, so the general adjoint functor theorem gives the reflection. The unit need not be injective or a topological embedding for an arbitrary $X$.