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@ghadishayban
Last active April 3, 2021 07:42
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"pmap for apis"
(defn iteration
"returns a channel of items given step!, a function of some (opaque continuation data) k
step! calls can get bufsize ahead of consumption (asynchronously)
step! - fn of k/nil to chan yielding (opaque) 'ret'
:bufsize - buffer this many step! calls, default 1
:some? - fn of ret -> truthy, indicating there is a value
will not call vsf/kf nor continue when false
default some?
:vsf - fn of ret -> vs, a collection of values produced by one step!, default c.c/vector
:kf - fn of ret -> next-k or nil (will not continue), default identity
:initk - the first value passed to step!, default nil
it is presumed that step! with non-initk is unreproducible/non-idempotent
if step! with initk is unreproducible, it is on the consumer to not consume twice"
[step!
& {:keys [vsf kf some? initk bufsize]
:or {vsf vector
kf identity
some? some?
initk nil
bufsize 1}}]
(let [bufch (chan bufsize)
ch (chan 100 cat)]
(pipe bufch ch)
(go
(loop [retc (step! initk)]
(let [ret (<! retc)]
(when-some [k (and (some? ret)
(>! bufch (vsf ret))
(kf ret))]
(recur (step! k)))))
(close! ch))
ch))
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