I see a ton of resources for learning clojure so I’m a bit lost on where to start… is there one in particular that’s recommended for people who already know fp in other languages and have a basic understanding of lisp?

http://4clojure.com has some good exercises, and when you solve them you can see other people's solutions

also be sure to check out the cheatsheet https://clojure.org/api/cheatsheet

cool! thanks for the links

@automattable and for books, Joy of Clojure is perfect for someone coming from ML or Common Lisp and learning Clojure

👍 I’m coming from haskell so that should be perfect

@automattable Have you worked on the JVM before? If not, that's probably going to be the biggest shift coming from Haskell, other than Clojure having no type system 🙂

not in a long time, but yes

what’s so different about the jvm that would cause me issues?

tbh, I’m expecting strict evaluation to be the thing that takes me longer to get used to

(and I will definitely miss my types :P)

Folks coming from non-JVM languages sometimes seem to struggle with tooling, classpaths, stacktraces etc.

I think it depends on how you look at it.

Some people do just fine.

Just putting it out there as a possible hurdle 🙂

ah I forgot about that sort of thing

I’ve heard the stacktraces can be rough

especially when macros get involved

And especially when you have lazy sequences in play 🙂 (re: your comment about strict evaluation)

maybe I’ll just only use total functions

heh

I personally feel the stacktraces aren't as bad as some people make out -- I think there are some heuristics you can quickly pick up to help ignore the "noise" in the stack traces.

So what brings you to Clojure from Haskell @automattable ?

interviewing for a clojure job soon

they claim I don’t need to know it going in, but I figure it can’t hurt

Nice!

I’m pretty excited about it 🙂

This is a good talk to watch about one of the unique aspects of Clojure https://vimeo.com/223309989

is there a good way to apply a vector of functions to corresponding members of a vector of values? i’m looking for

(f [inc dec square] [1 2 3])
> [2 1 9]

@jakeb (map #(%1 %2) [inc dec square] [1 2 3])

oh dang, of course

nice, thanks

hmm, follow up question then

is there an easier way to do

(map #(map (fn [f v] (f v)) [inc dec] %) [[1 2] [3 4]])
> ((2 1) (4 3))

?

ugh, it auto expanded, the input was (map #(map (juxt inc dec) %) ...)

but clearly juxt isn't what you want at all

i’d been thinking juxt too

but yeah it seems not right

is there any function like (defn f-of-x [f x] (f x))?

it’s not apply, because x isn’t a seq

yeah, #(%1 %2) is as close as you get

unless you count (.call f x) but that isn't an object, it's not first class

cool cool

oops

misremembered the name of the method at first

nice

thanks!

but to end up with something first class, you need to wrap it in a function, so you might as well embed (f x) instead of (.invoke f x)

is there some magic i’m not thinking of if that first function is identity?

as in,

(map #(map f-of-x [identity bt/pct-strs-to-num] %) vec-of-vecs)

earlier i actually had a map and was able to use clojure.algo.generic.functor.fmap

but now i’m just trying to map a function over the second item in each tuple in a vector

@jakeb I'm wondering if a reduce statement is a better fit for your scenario, but I'm not in a position to fully flesh out the options

hi there

I would like to use something like this (take 3 (iterate plus now (days 1))), that I found on the website https://github.com/dm3/clojure.java-time#an-appetizer

it says ArityException Wrong number of args (3) passed to: core/iterate clojure.lang.AFn.throwArity (AFn.java:429)

I understand that there are too many arguments for iterate

any good advise how to rewrite the function?

Too many or too few? The error message only tells you that there are a 'wrong number'.

I think iterate takes only two args

What does (doc iterate) say?

[f x]

should I try with a partial?

(take 3 (iterate inc 1)) -> 1 2 3

What are you trying to achieve? Determine the next three days, starting from today?

exactly

tried this (take 5 (iterate (partial plus now) (days 1)))

says ClassCastException java.time.LocalDate cannot be cast to java.time.temporal.TemporalAmount java-time.temporal/t-plus (temporal.clj:293)

so

(into {} [(vector 1 90)])
> {1 90}
(into {} [(list 1 90)])
> ClassCastException java.lang.Long cannot be cast to java.util.Map$Entry

what’s going on here?

vectors are interpreted as key/value pairs. notice:

user=> (seq {:a :a :b :b})
([:a :a] [:b :b])

so (into {} [(vector 1 90)]) is (into {} [[1 90]]) which is, in english, turn this vector of key/value pairs into a map, which is straight forward. but this notion of key/value pairs is not tied to sequential things but to vectors.

here's the java of the cons function on hashmap that is being called:

interesting

i’d been using vectors for my key value pairs but I’d figured that was just convention

not something real

ok cool, changed a map to a mapv upstream and everything’s great

thanks!

👍