object

expected(Reference)

Expected term reference predicates. Requires passing an expected reference constructed using the “expected” object as a parameter.

Author: Paulo Moura
Version: 1.1
Date: 2018/7/11
Compilation flags:
static, context_switching_calls

(no dependencies on other entities)

Public interface

is_unexpected/0

True if the expected reference holds an unexpected term. Avoid whenever possible by using instead the if_unexpected/1 predicate.

Compilation flags:
static
Mode and number of proofs:
is_unexpected - zero_or_one

is_expected/0

True if the expected reference holds an expected term. Avoid whenever possible by using instead the if_expected/1 predicate.

Compilation flags:
static
Mode and number of proofs:
is_expected - zero_or_one

if_unexpected/1

Applies a closure, with the expected reference term as additional argument, if it holds an unexpected term. Succeeds otherwise.

Compilation flags:
static
Template:
if_unexpected(Closure)
Meta-predicate template:
if_unexpected(1)
Mode and number of proofs:
if_unexpected(+callable) - zero_or_more

if_expected/1

Applies a closure, with the expected reference term as additional argument, if it does not hold an unexpected term. Succeeds otherwise.

Compilation flags:
static
Template:
if_expected(Closure)
Meta-predicate template:
if_expected(1)
Mode and number of proofs:
if_expected(+callable) - zero_or_more

unexpected/1

Returns the unexpected reference term if not an expected term. Throws an error otherwise.

Compilation flags:
static
Template:
unexpected(Unexpected)
Mode and number of proofs:
unexpected(--term) - one
Exceptions:
Expected reference holds an expected term:
existence_error(unexpected_term,Reference)

expected/1

Returns the expected reference term if not an unexpected term. Throws an error otherwise.

Compilation flags:
static
Template:
expected(Expected)
Mode and number of proofs:
expected(--term) - one
Exceptions:
Expected reference holds an unexpected term:
existence_error(expected_term,Reference)

map/2

When the expected reference does not hold an unexpected term and mapping a closure with the expected reference term and the new term as additional arguments is successful, returns an expected reference with the new value. Otherwise returns the expected reference.

Compilation flags:
static
Template:
map(Closure,NewReference)
Meta-predicate template:
map(2,*)
Mode and number of proofs:
map(+callable,--nonvar) - one

flat_map/2

When the expected reference does not hold an unexpected term and mapping a closure with the expected reference value and the new expected reference as additional arguments is successful, returns the new expected reference. Otherwise returns the expected reference.

Compilation flags:
static
Template:
flat_map(Closure,NewReference)
Meta-predicate template:
flat_map(2,*)
Mode and number of proofs:
flat_map(+callable,--nonvar) - one

or_else/2

Returns the expected reference term if it does not hold an unexpected term or the given default term if the expected reference holds an unexpected term.

Compilation flags:
static
Template:
or_else(Term,Default)
Mode and number of proofs:
or_else(--term,@term) - one

or_else_get/2

Returns the expected reference term if it does not hold an unexpected term or applies a closure to compute the term if the expected holds an unexpected term. Throws an error when the expected reference holds an unexpected term and a term cannot be computed using the given closure.

Compilation flags:
static
Template:
or_else_get(Term,Closure)
Meta-predicate template:
or_else_get(*,1)
Mode and number of proofs:
or_else_get(--term,+callable) - one
Exceptions:
Expected reference holds an unexpected term and a term cannot be computed:
existence_error(expected_term,Reference)

or_else_call/2

Returns the expected reference term if it does not hold an unexpected term or calls a goal deterministically if the expected reference holds an unexpected term. Can be used e.g. to throw the exception hold by the expected reference.

Compilation flags:
static
Template:
or_else_call(Expected,Goal)
Meta-predicate template:
or_else_call(*,0)
Mode and number of proofs:
or_else_call(--term,+callable) - zero_or_one

or_else_fail/1

Returns the expected reference term if it does not hold an unexpected term. Fails otherwise. Usually called to skip over empty expected reference holding unexpected terms.

Compilation flags:
static
Template:
or_else_fail(Expected)
Mode and number of proofs:
or_else_fail(--term) - zero_or_one

Protected interface

(none)

Private predicates

(none)

Operators

(none)

Remarks

(none)

See also

expected