eval args ( term, termInfo ) allows the user to pass args directly to the evaluation mechanism. This is useful if some kind of pre-processing is required. If you do not need to pre-process command line arguments, use one of exec or run. On failure the program exits.

exec ( term, termInfo ) executes a command line program, directly grabbing the command line arguments from the environment and returning the result upon successful evaluation of term. On failure the program exits.

run ( term, termInfo ) runs a term containing an IO action, performs the action, and returns the result on success. On failure the program exits.

unwrap args ( term, termInfo ) unwraps a Term without handling errors. The intent is for use in testing of Terms where the programmer would like to consult error state without the program exiting.

evalChoice args mainTerm choices is analogous to eval, but for programs that provide a choice of commands.

Analogous to exec, but for programs that provide a choice of commands.

Analogous to run, but for programs that provide a choice of commands.

Analogous to unwrap, but for programs that provide a choice of commands.

Information about the way a Term exited early. Obtained by either unwraping or unwrapChoiceing some Term. Handy for testing programs when it is undesirable to exit execution of the entire program when a Term exits early.