$\mathcal{C}\mathbb{R}$
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{-# LANGUAGE OverloadedStrings #-}
import Text.LaTeX
import Text.LaTeX.Packages.AMSMath
import Text.LaTeX.Packages.AMSSymb
import Text.LaTeX.Packages.AMSFonts
math $ mathcal "C" <> mathbb "R" :: LaTeX
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putStrLn "𝓒ℝ"
𝓒ℝ
(Rendering via HaTeX and LaTeX by MathJax)
import Math.LaTeX.Prelude
"" <> (𝓒<>ℝ) $<> "" :: LaTeX