clj-foundation.transducers — coconutpalm/clj-foundation 0.10.0

Utilities helping to make transducer functions out of regular functions. Transducers can be pipelined like thread-first or thread-list, but using regular function composition.

Unlike thread-first or thread-list, a pipeline of transducers processes a single elemnt through all functions at a time, eliminating the need to create multiple intermediate collections.

Also includes xreduce, a version of reduce that returns a transducer function (this function is seemingly missing from the standard library).

<-f clj

(<-f f)

Translate an arbitrary function f into a transducing function that can be composed into a transducer chain using (comp f1 f2 f3 ... fn).

For creating a reduce transducer with an initial value, pass a vector with the reducing function in the initial element and the initial value in the second element.

<-fns clj

(<-fns & fns)

Compute a transducer function composing fns according to Unix pipe semantics as defined in <-f.

xmapcat clj

(xmapcat f)

Return a transducer calling (mapcat f) for an arbitrary f. Results are interpreted as follows:

• If (f x) is a map, seq, or set, it is returned as-is.
• If (f x) is nil, patterns/nothing is returned.
• Otherwise, the result is wrapped in a vector and returned.

xreduce clj

(xreduce f)

(xreduce f initial-value)

A version of reduce that returns a transducer function. There are two arities of this function, one accepting a single reducer function and one that accepts a reducer function and an initial value. Just like the transducer-producing arities in the standard library (e.g.: map, mapcat), this function does not include an arity accepting an input collection.

Semantics of the transducer function reduce are the same as the semantics of a regular reduce.