\installprettytype [LAM] [LAM]
% Define \startlambda \stoplambda
\definetyping[lambda][option=LAM,style=sans,before=\startboxed,after=\stopboxed]
+% Define \startunboxedlambda \stopunboxedlambda
+\definetyping[unboxedlambda][option=LAM,style=sans]
% Define \lam{} (since \lambda is taken)
\definetype[lam][option=LAM,style=sans]