time.calendar_duration -- value representing a duration in the ISO 8601
calendar

time.Clock -- class of effects that implement a clock

This is a `ref` feature such that code that requires an arbitrary `Clock`
effect could be written in a way that permits its execution using different
actual `Clock` implementations like `time.nano` that provides high
precision with low accuray or a different clock that provides higher accuracy.

Represents a date and a time in the Gregorian calendar, without any specification of
a time zone or reference point.

time.duration -- value representing a duration, i.e., a time span

This is intended for high precision time specification and measurement, it
uses a time resolution of 1ns.

The maximum value is about 580 years, so this is not intended for use in
calendars that may require time spans exceeding several centuries or millennia,
nor astrological time spans.

time.frequncy -- a child of Period that is defined by a frequency per duration

This provices abstract features that define a period of time and that
permit multiplications with large integers avoiding drift.

An example is a frequency of 60Hz that can be specified as


This is different to `duration.s 1 / 60` since `duration` can only be represented as
`16666667 ns`, resulting in a drift of 1/3ns per period. This would result in a drift
of 17ms (a whole period) in 10 days. Such inaccuracy can result in catastrophic failure, see
(The Patriot Missile Failure)[https://www-users.cse.umn.edu/~arnold/disasters/patriot.html].

time.histogram -- feature to collect and output timing data

This is particularly useful to analyse variations in release or
execution times of repeatedly executed tasks or events.

For this, it distributes time.duration values into a list of
buckets that correspond to different ranges of durations. These
buckets may be equally spaced (linear) or growing by an equal
factor (logarithmic).

The use of buckets permits the collection of large numbers of
sampe durations since only the counts per bucket are recorded

time.instant -- abstract moment in time used for measuring durations

An instant is an absolute time relative to some fixed start of an epoch
that depends on the clock that created this instant.

NYI: UNDER DEVELOPMENT: we might want to add a reference to the clock that
created this instant and verify that `infix -` is called only on `instant`s
created by the same clock.

time.nano -- effect providing nano time

time.nano is a timer that provides high precision but possibly low
accuracy. Such a timer is typically useful for timing the duration
of events, such as measuring the time it takes to perform some
calculation.

time.nano may have a significant drift compared to actual time, it might
not be the right source of time to, e.g., feed an alarm clock that should
wake you up at 6h30 every morning.

abstract handler that can deliver a nano time

effect for getting the current date_time

time.Period -- template for periods

This provices abstract features that define a period of time and that
permit multiplications with large integers avoiding drift.

An example is a period of 1/60sec. Using `time.duration`, which is a child
of `Period`, this can only be represented as `16666667 ns`, resulting in
a drift of 1/3ns per period, which would result in a drift of 1.7ms (a whole
period) per day. Such inaccuracy can result in catastrophic failure, see
(The Patriot Missile Failure)[https://www-users.cse.umn.edu/~arnold/disasters/patriot.html].

time.duration.unit -- unit type defining units used in duration

time units used to present durations as Strings to humans to read

create a String from this instance. Unless redefined, `a.as_string` will
create `"instance[T]"` where `T` is the dynamic type of `a`

dynamic_apply -- apply `f.call` to `Any.this`'s dynamic type and value

This can be used to perform operation on values depending on their dynamic
type.

Here is an example that takes a `Sequence Any` that may contain boxed values
of types `i32` and `f64`. We can now write a feature `get_f64` that extracts
these values converted to `f64` and build a function `sum` that sums them up
as follows:


NYI: IMPROVEMENT: #5892: If this is fixed, we could write

Get the dynamic type of this instance. For value instances `x`, this is
equal to `type_of x`, but for `x` with a `ref` type `x.dynamic_type` gives
the actual runtime type, while `type_of x` results in the static
compile-time type.

There is no dynamic type of a type instance since this would result in an
endless hierarchy of types. So for Type values, dynamic_type is redefined
to just return Type.type.

is the given date valid?

short-hand for accessing time.nano effect in current environment

get the current date_time.
Uses currently installed time.now effect
or installs the default_now handler

convenience prefix operator to create a string from a value.

This permits usage of `$` as a prefix operator in a similar way both
inside and outside of constant strings: $x and "$x" will produce the
same string.

stopwatch measures the execution duration of f

stopwatch measures the execution duration of f

string representation of this type to be used for debugging.

result has the form "Type of '<name>'", but this might change in the future

There is no dynamic type of a type instance since this would result in an
endless hierarchy of types, so dynamic_type is redefined to just return
Type.type here.

Is this type assignable to a type parameter with constraint `T`?

The result of this is a compile-time constant that can be used to specialize
code for a particular type.


it is most useful in conjunction with preconditions or `if` statements as in


or

name of this type, including type parameters, e.g. 'option (list i32)'.

convenience prefix operator to create a string from a value.

This permits usage of `$` as a prefix operator in a similar way both
inside and outside of constant strings: $x and "$x" will produce the
same string.

NYI: Redefinition allows the type feature to be distinguished from its normal counterpart, see #3913

Get a type as a value.

This is a feature with the effect equivalent to Fuzion's `expr.type` call tail.
It is recommended to use `expr.type` and not `expr.type_value`.

`type_value` is here to show how this can be implemented and to illustrate the
difference to `dynamic_type`.