\[ \newcommand{\tr}{\Rightarrow} \newcommand{\trs}{\tr^{\!\ast}} \newcommand{\rlnm}[1]{\mathsf{(#1)}} \newcommand{\rred}[1]{\xrightarrow{#1}} \newcommand{\rreds}[1]{\mathrel{\xrightarrow{#1}\!\!^*}} \newcommand{\cl}{\mathsf{Cl}} \newcommand{\pow}{\mathcal{P}} \newcommand{\matches}{\mathrel{\mathsf{matches}}} \newcommand{\kw}[1]{\mathsf{#1}} \]

Concrete While Loops

    while (x > 0) { 
      x = x-1; 
      y = y+1; 
    } 

    while x > 0:
      x = x - 1
      y = y + 1

    while !x > 0 do 
      x := !x - 1
      y := !y + 1
    done 

    while x > 0 loop
      x := x - 1;
      y := y - 1;
    end loop