\RequirePackage{amssymb}

\let\eventually\lozenge
\let\always\square
\def\until{\mathop{\mathsf U}}
\def\untilW{\mathop{\mathsf W}}

\let\then\Rightarrow

\def\potentially{\exists\eventually}
\def\inevitably{\forall\eventually}
\def\potentiallyalways{\exists\always}
\def\invariantly{\forall\always}

% The below is taken from the circle package; https://www.ctan.org/pkg/circle
% However, circle is not available in texlive, so this is easier.
\newcommand*\Circle[1][n]{%
  \mathchoice{\@Circle{#1}{\tf@size}}{\@Circle{#1}{\tf@size}}%
             {\@Circle{#1}{\sf@size}}{\@Circle{#1}{\ssf@size}}%
}

% Bugs: circles have size n at fontsize 2n-1 and 2n; they do not scale linearly
%       depending on the fontsize

\newcommand*\@Circle[2]{{%
  \dimen0=#2pt \advance\dimen0by4.5pt \dimen1=1pt \divide\dimen0by\dimen1
  \count255=\dimen0 \ifodd\count255 \advance\count255by1 \fi\divide\count255by2
  \ifnum\count255=0 {}\else\ifnum\count255>15 {}\else
    \dimen0=\count255pt
    \edef\circfont{tencirc\ifnum\count255>8 w\fi}
    \advance\count255by\if #1f111\else 95\fi
    \dimen2=.82\dimen0 \advance\dimen2by.4pt
    \raisebox{.5\dimen0}[\dimen2]{\makebox[1.2\dimen0]{%
      \hspace*{.9\dimen0}%
      \csname\circfont\endcsname
      \char\count255 %
    }}%
  \fi\fi
}}

\let\next\Circle

\let\eval\Downarrow
\def\mlif#1#2#3{\mathbf{if}\;#1\;#2\;#3}
\def\mllet#1#2#3{\mathbf{let}\;\mathit{#1}=#2\;\mathbf{in}\;#3}
\def\Bool{\mathbf{Bool}}