77 lines
No EOL
2.5 KiB
Elm
77 lines
No EOL
2.5 KiB
Elm
-- Library for working with time. Type `Time` represents some number of milliseconds.
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module Time where
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import open Basics
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import Native.Time
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import Signal (Signal)
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-- Type alias to make it clearer when you are working with time values.
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-- Using the `Time` constants instead of raw numbers is very highly recommended.
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type Time = Float
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-- Units of time, making it easier to specify things like a
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-- half-second `(500 * milliseconds)` without remembering Elm’s
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-- underlying units of time.
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millisecond : Time
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millisecond = 1
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second : Time
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second = 1000 * millisecond
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minute : Time
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minute = 60 * second
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hour : Time
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hour = 60 * minute
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inMilliseconds : Time -> Float
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inMilliseconds t = t
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inSeconds : Time -> Float
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inSeconds t = t / second
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inMinutes : Time -> Float
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inMinutes t = t / minute
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inHours : Time -> Float
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inHours t = t / hour
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-- Takes desired number of frames per second (fps). The resulting signal
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-- gives a sequence of time deltas as quickly as possible until it reaches
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-- the desired FPS. A time delta is the time between the last frame and the
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-- current frame.
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fps : number -> Signal Time
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fps = Native.Time.fps
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-- Same as the fps function, but you can turn it on and off. Allows you
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-- to do brief animations based on user input without major inefficiencies.
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-- The first time delta after a pause is always zero, no matter how long
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-- the pause was. This way summing the deltas will actually give the amount
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-- of time that the output signal has been running.
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fpsWhen : number -> Signal Bool -> Signal Time
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fpsWhen = Native.Time.fpsWhen
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-- Takes a time interval t. The resulting signal is the current time,
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-- updated every t.
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every : Time -> Signal Time
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every = Native.Time.every
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-- Takes a time `t` and any signal. The resulting boolean signal
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-- is true for time `t` after every event on the input signal.
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-- So ``(second `since` Mouse.clicks)`` would result in a signal
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-- that is true for one second after each mouse click and false
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-- otherwise.
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since : Time -> Signal a -> Signal Bool
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since = Native.Time.since
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-- Add a timestamp to any signal. Timestamps increase monotonically. Each
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-- timestamp is related to a specfic event, so `Mouse.x` and `Mouse.y` will
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-- always have the same timestamp because they both rely on the same
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-- underlying event.
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timestamp : Signal a -> Signal (Time, a)
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timestamp = Native.Time.timestamp
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-- Delay a signal by a certain amount of time. So `(delay second Mouse.clicks)`
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-- will update one second later than any mouse click.
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delay : Time -> Signal a -> Signal a
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delay = Native.Time.delay |