assertMsg :: Bool -> String -> Bool Print a trace message if pred is false. Intended to be used to augment asserts with helpful error messages. pred Condition under which the msg should not be printed. msg Message to print. trace: foo is not bar, silly stderr> assert failed ]]>

assertOneOf :: String -> String -> StringList -> Bool Specialized asserts.assertMsg for checking if val is one of the elements of xs. Useful for checking enums. name The name of the variable the user entered val into, for inclusion in the error message. val The value of what the user provided, to be compared against the values in xs. xs The list of valid values. false stderr> trace: sslLibrary must be one of "openssl", "libressl", but is: "bearssl" ]]>