Applying a style to all math blocks in an environment

Question

I'm writing a math paper, and I want to change the style for the statement of theorems to \tt. However, I want this to affect things within math mode as well as normal text. Is there some way to force all math blocks within an environment to change style?

Answer 1

Here's one possible solution implementing the idea proposed by Marco Daniel in a comment; the solution uses:

1. The amsthm package to define a new theorem style to produce theorem-like structures with heading and body text in monospaced font. This style is used to define a theo environment.

2. The etoolbox package to append David Carlisle's answer to Can I change all math output to use monospaced text? to a hook executed by the \begin command at the beginning of the theo environmet.

   \documentclass{article}
   \usepackage{amsthm}
   \usepackage{etoolbox}
   
   \newtheoremstyle{monosp}
     {\topsep}{\topsep}
     {\ttfamily}{}
     {\ttfamily}{.\mbox{$ $}}
     {.5em}{}
   \theoremstyle{monosp}
   \newtheorem{theo}{Theorem}
   
   \AtBeginEnvironment{theo}{%
   \everymath{\mathtt{\xdef\tmp{\fam\the\fam\relax}\aftergroup\tmp}}
   \everydisplay{\mathtt{\xdef\tmp{\fam\the\fam\relax}\aftergroup\tmp}}
   }
   
   \begin{document}
   
   Some test text $a=b$ and some in-line math $c=d$ and a displayed expression
   \[a=b\]
   just to test.
   \begin{theo}
   Some test text $a=b$ and some in-line math $c=d$ and a displayed expression
   \[a=b\]
   just to test.
   \end{theo}
   Some test text $a=b$ and some in-line math $c=d$ and a displayed expression
   \[a=b\]
   just to test.
   
   \end{document}