Questions tagged [transducer]
83 questions
8
votes
2 answers
What is the 'parallel' concept in Rich Hickey's transducers Strange Loop talk?
In the Strange Loop presentation on Transducers Rich Hickey mentions at a concept in a table called 'parallel'.
You can easily see examples of seqs and into and channels using transducers.
Now you can work out that Observables are talking about…
hawkeye
- 34,745
- 30
- 150
- 304
7
votes
1 answer
Whatever happened to `Observable.transduce` in RxJS v5+?
RxJS v4 used to have an Observable.transduce method which took a transducer. This allowed the use of library-independent transducer operators which had major performance benefits in the…
Kevin Ghadyani
- 6,829
- 6
- 44
- 62
7
votes
1 answer
Are Clojure transducers eager?
In this blog entry, "CSP and transducers in JavaScript", the author states:
First, we have to realise that many array (or other collection) operations like map, filter and reverse can be defined in terms of a reduce.
So then we see a number of…
hawkeye
- 34,745
- 30
- 150
- 304
6
votes
0 answers
Transducers: What should the completion arity do if the nested step arity has returned reduced?
A stateful transducer is expected to flush its state by calling the "step" arity (i.e. [([result input] ) ) as many times as needed, before calling the "complete" arity (i.e. ([result] )).
My question is how early termination (with reduced) is to be…
drRobertz
- 3,490
- 1
- 12
- 23
6
votes
1 answer
Understanding Clojure Transducer Performance
At a high level I understood that using a transducer does not create any intermediate data structures whereas a long chain of operations via ->> does and thus the transducer method is more performant. This is proven out as true in one of my examples…
burbma
- 63
- 1
- 3
6
votes
1 answer
Why is my transducer function slower than using ->> operator?
While solving problem from Hackkerank (https://www.hackerrank.com/challenges/string-compression/problem) I've written 2 implementations with and without transducers.
I was expecting the transducer implementation to be faster, than the function…
denis631
- 1,765
- 3
- 17
- 38
6
votes
1 answer
In Clojure, how can I do a performant version of `frequencies` with transducers?
(Question credit: Fernando Abrao.)
I hear about the performance benefits of transducers in Clojure, but I'm not sure how to use them.
Say I have a qos/device-qos-range function that returns sequence of maps, some of which contain a decimal…
Jeff Terrell Ph.D.
- 2,563
- 26
- 39
6
votes
1 answer
Using Clojure Tranducers to parse big files: OutOfMemory Error
I want to parse a big json file (3GB) and return a hash-map for each line in this file. My intuition was to use a transducer to process the file line-by-line and construct a vector with some selected fields (> 5% of bytes in the file).
However, the…
user5239066
6
votes
1 answer
Transducers in Haskell and the monomorphism restriction
I implemented transducers in Haskell as follows:
{-# LANGUAGE RankNTypes #-}
import Prelude hiding (foldr)
import Data.Foldable
type Reducer b a = a -> b -> b
type Transducer a b = forall t. Reducer t b -> Reducer t a
class Foldable c =>…
Aadit M Shah
- 72,912
- 30
- 168
- 299
5
votes
2 answers
eduction vs transducer composition
Whats the difference between:
(transduce (comp fn-1 fn-2 fn-3) conj vector-collection)
and
(eduction fn-1 fn-2 fn-3 vector-collection)
I've read the eduction docs but didn't understand the purpose of the eduction.
sumek
- 26,495
- 13
- 56
- 75
4
votes
2 answers
Why does compose apply left to right with transducers?
Example code:
// Compose functionality
const compose = (...fns) => {
return args => {
return fns.reduceRight((arg, fn) => fn(arg), args);
}
};
// List of transformation and predicate functions
const add1 = x => x + 1;
const…
FNMT8L9IN82
- 483
- 1
- 9
- 22
4
votes
1 answer
Difference between Transducer and NFA
Can someone tell me how a Transducer differs from a NFA?
samsamara
- 4,630
- 7
- 36
- 66
4
votes
2 answers
Is there a reducing function in Clojure that performs the equivalent of `first`?
I'm often writing code of the form
(->> init
(map ...)
(filter ...)
(first))
When converting this into code that uses transducers I'll end up with something like
(transduce (comp (map ...) (filter ...)) (completing #(reduced %2)) nil…
Sebastian Oberhoff
- 1,271
- 1
- 10
- 16
4
votes
1 answer
What does completing function do in Clojure?
I've came across completing function on clojuredocs but there is no doc at the moment.
Could you provide some examples?
Ertuğrul Çetin
- 5,131
- 5
- 37
- 76
4
votes
1 answer
Clojure reduce transducer
I am looking for a simple example of transducers with a reducing function.
I was hoping that the following would return a transducing function, since (filter odd?) works that way :
(def sum (reduce +))
clojure.lang.ArityException: Wrong number of…
nha
- 17,623
- 13
- 87
- 133