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total                                                            (Lib)
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total : ('a -> 'b) -> 'a -> 'b option

SYNOPSIS
Converts a partial function to a total function.

KEYWORDS
Exception, error handling, total function.

DESCRIBE
In ML, there are two main ways for a function to signal that it has been
called on an element outside of its intended domain of application:
exceptions and options. The function {total} maps a function that may
raise an exception to one that returns an element in the option type.
Thus, if {f x} results in any exception other than {Interrupt} being
raised, then {total f x} returns {NONE}. If {f x} raises {Interrupt},
then {total f x} likewise raises {Interrupt}. If {f x} returns {y}, then
{total f x} returns {SOME y}.

The function {total} has an inverse {partial}. Generally speaking,
{(partial err o total) f} equals {f}, provided that {err} is the only
exception that {f} raises. Similarly, {(total o partial err) f} is equal
to {f}.

FAILURE
When application of the first argument to the second argument raises
{Interrupt}.

EXAMPLE

- 3 div 0;
! Uncaught exception:
! Div

- total (op div) (3,0);
> val it = NONE : int option

- (partial Div o total) (op div) (3,0);
! Uncaught exception:
! Div


SEEALSO
Lib.partial.

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