I just wrote a beginner-focused blog post on how destructuring works (one of many, I know). feedback welcome! https://paultopia.github.io/posts-output/destructuring/

@seancorfield solved

now I hope someone can think with me how to make this a function and a test.

(defn let-it-be
  "Can you bind x, y, and z so that these are all true?"
  []
  (let [x 7
        y 3
        z 1]
    (and (= 10 (let x y (+ x y)))
         (= 4 (let y z (+ y z)))
         (= 1 (let z z)))))  

I could do

(defn let-it-be  "Can you bind x, y, and z so that these are all true?"  []  (let [x 7        y 3        z 1] 

but then x y z are still not resolved

and I have no clue how to inject the solution in the test then

is there a clojure fn that would convert

{:x {:y {:z 1}
:z 2} :z 3} 

{[:x :y :z] 1
[:x :z] 2
[:z] 3} 

@kokos have you tried partition-by ?

@roelofw, cant say i see how i could use partition-by for what i need to accomplish

@kokos perhaps you can create a walker that traverses the map from top to bottom? That way you could put the keys in a vector i believe

It has some nice pre and post level functions as well

(defn prepred [pk r [k v]]
 (if-not (map? v)
  (assoc r (conj pk k) v)
  (reduce (partial prepred (conj pk k)) r v)))
(defn transf [x]
 (reduce (partial prepred []) {} x))
 
(transf {:x {:y {:z 1} :z 2} :z 3})

how can i make boot repl start in my main ns instead of the user ns?

some expert who can help me ?

what unresolved error are you seeing?

At some wierd way I cannot find the function list-conj in the test file @dpsutton

is it defined above your tests?

no, in another file which I require

all the other files before this where found in the tests

can you tell me what the error is?

exactly the error message?

moment

Wierd, when running the tests there are no error messages

but I see on the code that the functions have another color indicating that there is a error.

and on the tooltip there is a non-resolved error

oke, problem is solved. There were some parentheses missing

are sets not part of core ? When I test a function I see this error message :

java.lang.ClassNotFoundException: clojure.set 

it is in a test file which only ns line is this :

(ns forclojure.elementary2-test
  (:require [clojure.test :refer :all]
            [forclojure.elementary2 :refer :all])) 

it complaing about this line :

(is (= (intro-to-sets) (clojure.set/union #{:a :b :c} #{:b :c :d})))) 

@seancorfield I’m still a little confused and looking for a definite answer on where I should create my database environment. Should I create all of my db environment through my application or is this something that you typically create beforehand and your application sits on top/references?

is this a good way to require set :

(ns forclojure.elementary2-test
  (:require [clojure.test :refer :all]
            [forclojure.elementary2 :refer :all]
            [clojure.set :refer :all])) 

I have this function :

(= [2 4] (let [[a b c d e] [0 1 2 3 4]] __))  

I know the answer is [c e] . But when I make a function like this (identity [c e] ) I see a message that [ c e] cannot be resolved

How can I solve this in a function which do not take any parameters

why do you need a function?

and how to I make a function that takes two arguments [ v m] and [ v, m ] does not work

why not just (let [[a b...][0 1 ...]] [ce])

I try to make my private repo of 4 clojure challenges and I try to make one file with the solutions and one with tests

but maybe it is not handy here

oh, so you're putting in a different file to return [c e] where c and e are not defined

yes

maybe just skip this one then

but as I said it not the best way to store this challenge

there's really no benefit to it

unless you put the whole let binding into the function

why not (= [2 4] (answers/question5)

and (defun question5 [] (let [[a b c d e] [ 0 1 2 3 4 5]] [c e])

oke, I can do that also

@dpsutton can you also help me with this

I have a function which takes a map and a value

How do I make this work on the parameters part [ v m ] or [ v , m ] does not work

?

it's about this code :

(defn map-defaults
  "When retrieving values from a map, you can specify default values in case the key is not found:
  \n\n(= 2 (:foo {:bar 0, :baz 1} 2))\n\nHowever, what if you want the map itself to contain the default values?
  Write a function which takes a default value and a sequence of keys and constructs a map."
  []
  [v m]
  (zipmap m (repeat v)))  

Could someone help me understand what I'm doing wrong with Java interop? I'm trying to translate this:

java
PDFont font = PDTrueTypeFont.loadTTF(document, "Arial.ttf");

clojure
(.loadTTF PDTrueTypeFont document "Arial.ttf")

I see a message on my cursive ide that v and m are not resolved

I saw it . I had two parameters parts, Sorry for the question

Why do I see this error in this test file :

(testing "rearrenging code"
    (is ( (rearranging_code) (sort (rest (reverse [2 5 4 1 3 6]))))
        (-> [2 5 4 1 3 6] (reverse) (rest) (sort) ((rearranging_code)))))  

I try to test this function :

(defn rearranging_code
  "The -> macro threads an expression x through a variable number of forms. First, x is inserted as the second item
  in the first form, making a list of it if it is not a list already. Then the first form is inserted as the second
   item in the second form, making a list of that form if necessary. This process continues for all the forms.
   Using -> can sometimes make your code more readable."
  []
  (identity 5))  

and the error message is this :

actual: java.lang.ClassCastException: java.lang.Long cannot be cast to clojure.lang.IFn  

you are missing an equal

you are trying to call the return value of rearranging_code which is 5

also, note that (identity x) is x. so the function doesn't do anything, so you can just return x instead of (identity x)

and you call rearranging code twice, once so that it is the head of the list so therefore a function in the first form after the is, and second at the end of a threading macro but you are invoking it and threading the result, which is 5

and your is form has no test in it like equals

use the repl to figure out what the forms should look like

@dpsutton can you give me a hint where the = must be .

I tried

(testing "rearrenging code"
    (is ( =  (rearranging_code) (sort (rest (reverse [2 5 4 1 3 6]))))
        (-> [2 5 4 1 3 6] (reverse) (rest) (sort) ((rearranging_code))))) 

and

(testing  "rearrenging code"
    (is (   (rearranging_code) ( = (sort (rest (reverse [2 5 4 1 3 6]))))
        (-> [2 5 4 1 3 6] (reverse) (rest) (sort) ((rearranging_code))))))  

but both does not work

you're asserting that two things are equal

(is (= A B)

or (is true)

so pass to the is form something that is true

(is (= (my-crazy-contraption) (their-crazy-contraption)))

oke

then this schould be working I think

(testing "rearrenging code"
    (is ( =  (rearranging_code) (sort (rest (reverse [2 5 4 1 3 6])))
        (-> [2 5 4 1 3 6] (reverse) (rest) (sort) ((rearranging_code)))))) 

but still the same error message : actual: java.lang.ClassCastException: java.lang.Long cannot be cast to clojure.lang.IFn

((rearranging_code)) = (5) => cannot cast long to function

you are calling (5) which is meaningless

also, based on indentation, your equal doesn't include the second form with the threading macro

sorry, I do not understand what you mean

(is (= thing thing) ... more stuff to the is that are not in the equal form)

when I do only rearranging_code then it will also not be 5 because the function is not applied to my knowlegde

can you call rearranging code from the repl?

it should return five

it is (identify 5) from your definition above

yes, and I need ( is (= thing thing thing))

ah then the identatoin is misleading

no, it is (identity 5) not (identify 5)

yes, which returns 5

evaluate that on the repl

yes

I did already and it does

and this does also returns 5 (sort (rest (reverse [2 5 4 1 3 6])))

(sort (rest (reverse [2 5 4 1 3 6]))) (1 2 3 4 5)

how could it?

even as this : (-> [2 5 4 1 3 6] (reverse) (rest) (sort))

it reverses it, takes rest

and then sorts the vector

oke, back to the beginning : this is the challenge I have solved

(= (__ (sort (rest (reverse [2 5 4 1 3 6]))))
   (-> [2 5 4 1 3 6] (reverse) (rest) (sort) (__))
   5) 

the answer is last

right ?

looks like it

instead of returning (identity 5) why not just return last from your function then

I tried to make a function that returns last

but I did not get it work

so I thought I make a test where I test that both returns 5

then I could make a function that returns 5

(defn returns-last [] last)

defn returns-last [] last) #'cljc-bug.core/returns-last cljc-bug.core> ((returns-last) [1 2 3 4 5]) 5

Thanks, and now this test is also working

(testing "rearrenging code"
    (is (= ( (rearranging_code) (sort (rest (reverse [2 5 4 1 3 6]))))
           (-> [2 5 4 1 3 6] (reverse) (rest) (sort) ((rearranging_code)))
           5))) 

awesome

Finnaly I can put al my rewritten challenges to github

and can make new ones

@dpsutton thanks, you saved my day

anytime