org.purefn.kurosawa.util
Miscellaneous utility functions.
Miscellaneous utility functions.
chainclj
(chain & steps)Returns a function that when executed will perform a reversable process composed of a sequence of steps.
stepsA sequence of 1 argument functions with side effects.
On success, each step function should return a vector [result revert-fn]
where:
resultIf non-nil, the value passed to the next step in the process.revert-fnIf non-nil, a no-arg function which when executed will reverse the side effects of the step function.
The chain process proceeds by executing the first step function with the
initial value. If the result part of the return value is non-nil,
this value will be used as the argument for the next step function in the
sequence. This repeats until all step functions have been executed
successfully.
If during this process the a step function fails, the revert-fn function
for all previous steps will be called in the reverse order of execution.
This way all side effects of the entire process will be safely undone. Any
previous step's revert-fn who's value is nil will be ignored.
A step function is considered to have failed if:
- The
resultportion of the value returned by the step function is nil. - The entire return value of the step function is nil.
- The step function throws an exception.
The function returned will take the following arguments:
initialThe value passed to the first step.optsOptional arguments::debug trueturns on verbose logging.
When executed, it will return the result portion of the last successful
step or nil if there is a failure and the process is reverted.
Returns a function that when executed will perform a reversable process
composed of a sequence of steps.
- `steps` A sequence of 1 argument functions with side effects.
On success, each step function should return a vector `[result revert-fn]`
where:
- `result` If non-nil, the value passed to the next step in the process.
- `revert-fn` If non-nil, a no-arg function which when executed will
reverse the side effects of the step function.
The chain process proceeds by executing the first step function with the
`initial` value. If the `result` part of the return value is non-nil,
this value will be used as the argument for the next step function in the
sequence. This repeats until all step functions have been executed
successfully.
If during this process the a step function fails, the `revert-fn` function
for all previous steps will be called in the reverse order of execution.
This way all side effects of the entire process will be safely undone. Any
previous step's `revert-fn` who's value is nil will be ignored.
A step function is considered to have failed if:
- The `result` portion of the value returned by the step function is nil.
- The entire return value of the step function is nil.
- The step function throws an exception.
The function returned will take the following arguments:
- `initial` The value passed to the first step.
- `opts` Optional arguments: `:debug true` turns on verbose logging.
When executed, it will return the `result` portion of the last successful
step or nil if there is a failure and the process is reverted.defprintercljmacro
(defprinter c f)Overrides the print methods of class c with function f.
Useful for avoiding the printing of large defrecords in logs and the REPL.
Overrides the print methods of class `c` with function `f`. Useful for avoiding the printing of large `defrecord`s in logs and the REPL.
flipclj
(flip f)Returns a function which applies its arguments in reversed order from the
original function f.
(= ((flip vector) 1 2 3) [3 2 1])
Returns a function which applies its arguments in reversed order from the original function `f`. ```(= ((flip vector) 1 2 3) [3 2 1])```
revertibleclj
(revertible apply-fn revert-fn)Takes an application function and revert function, and returns a
revertible function suitable for use as part of a chain.
Takes an application function and revert function, and returns a revertible function suitable for use as part of a `chain`.
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