flatland.useful.state
periodic-recomputeclj
(periodic-recompute f duration)Takes a thunk and a duration (from flatland.useful.time), and yields a function that attempts to pre-cache calls to that thunk. The first time you call the returned function, it starts a background thread that re-computes the thunk's result according to the requested duration.
If you call the returned function with no arguments, it blocks until some cached value is available; with one not-found argument, it returns the not-found value if no cached value has yet been computed.
Take care: if the duration you specify causes your task to be scheduled again while it is still running, the task will wait in a queue. That queue will continue to grow unless your task is able to complete more quickly than the duration you specified.
Takes a thunk and a duration (from flatland.useful.time), and yields a function that attempts to pre-cache calls to that thunk. The first time you call the returned function, it starts a background thread that re-computes the thunk's result according to the requested duration. If you call the returned function with no arguments, it blocks until some cached value is available; with one not-found argument, it returns the not-found value if no cached value has yet been computed. Take care: if the duration you specify causes your task to be scheduled again while it is still running, the task will wait in a queue. That queue will continue to grow unless your task is able to complete more quickly than the duration you specified.
trade!clj
(trade! atom f & args)Like swap!, except it returns the old value of the atom.
Like swap!, except it returns the old value of the atom.
volatileclj
(volatile x)(volatile x & options)Creates and returns a Volatile with an initial value of x and zero or more options (in any order):
:meta metadata-map
:validator validate-fn
If metadata-map is supplied, it will become the metadata on the Volatile. validate-fn must be nil or a side-effect-free fn of one argument, which will be passed the intended new state on any state change. If the new state is unacceptable, the validate-fn should return false or throw an exception.
Creates and returns a Volatile with an initial value of x and zero or more options (in any order): :meta metadata-map :validator validate-fn If metadata-map is supplied, it will become the metadata on the Volatile. validate-fn must be nil or a side-effect-free fn of one argument, which will be passed the intended new state on any state change. If the new state is unacceptable, the validate-fn should return false or throw an exception.
with-altered-rootscljmacro
(with-altered-roots bindings & body)Use alter-var-root to temporarily modify the root bindings of some vars. For each var, the temporary value will be (apply f current-value args).
bindings should be a vector, each element of which should look like a function call: (with-altered-roots [(+ x 10)] body) ;; sets x to (+ x 10)
Use with caution: this is not thread-safe, and multiple concurrent calls can leave vars' root values in an unpredictable state.
Use alter-var-root to temporarily modify the root bindings of some vars. For each var, the temporary value will be (apply f current-value args). bindings should be a vector, each element of which should look like a function call: (with-altered-roots [(+ x 10)] body) ;; sets x to (+ x 10) Use with caution: this is not thread-safe, and multiple concurrent calls can leave vars' root values in an unpredictable state.
with-altered-varscljmacro
(with-altered-vars bindings & body)Binds each var-name to the result of (apply f current-value args) for the dynamic scope of body. Basically like swap! or alter, but for vars. bindings should be a vector, each element of which should look like a function call:
(with-altered-vars [(+ x 10)] body) ;; binds x to (+ x 10)
Binds each var-name to the result of (apply f current-value args) for the dynamic scope of body. Basically like swap! or alter, but for vars. bindings should be a vector, each element of which should look like a function call: (with-altered-vars [(+ x 10)] body) ;; binds x to (+ x 10)
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