If I pick up a book circa 2012, am I missing out a lot or possibly learning a lot of bad and outdated things?

Depends on the book...

There certainly has been quite a lot of movement in the ecosystem since then...

It’s likely that books targets Clojure 1.3 or maybe 1.4 so you can see what’s been added since here https://github.com/clojure/clojure/blob/master/changes.md @kamuela

(compojure/POST "/:foo" [x y & z :as request]
    (println "testing 1 12 3")
    (def yo request)
    (str "x-> " x "\ny-> " y "\nz-> " z "\nrequest-map:\n" request))

(compojure/POST "/:foo" request
     (let [[x y & z] request]
       (println "testing 1 12 3")
       (def yo request)
       (str "x-> " x "\ny-> " y "\nz-> " z "\nrequest-map:\n" request)))

and I get this error

<h2>HTTP ERROR: 500</h2>
<p>Problem accessing /arg. Reason:
<pre>    nth not supported on this type: PersistentHashMap</pre></p>

@tmtwd: I'm having a hard time seeing a difference between those two code fragments... did you mean to post two different things?

(compojure/POST "/:foo" request
     (let [[x y & z] request]
       (println "testing 1 12 3")
       (def yo request)
       (str "x-> " x "\ny-> " y "\nz-> " z "\nrequest-map:\n" request)))

sorry I meant to post that

this one doesn’t work

(I updated the post to fix the error)

It's because compojure treats vectors differently: https://github.com/weavejester/compojure/wiki/Destructuring-Syntax#compojure-specific-destructuring

ok

thanks

It's a macro, so normal Clojure destructuring doesn't apply directly.

ah I see

it maps directly to the params map

(I didn't know, I had to go look it up)

thanks

check out http://hashcode.withgoogle.com

maybe it will be interesting with clojure

(if (t/before? (t/now) (f/parse iso-8601 starts_at))
                         "Match scheduled"
                         (if (t/before? (f/parse iso-8601 ends_at) (t/now)) "Match is over" "Match is in progress”))

nesting of ifs is not good idea i guess, but the problem is in weird behaviour

also ends_at and starts_at are valid dates

nesting is fine

make sure you understand if and when and how to execute more than one form

> how to execute more than one form

what do you mean? ain’t forms evaluated recursively?

like (3rd(2nd(1st)))

that's not recursion

(that's nesting)

well, but the order is correct?

can you give some examples where it doesn't work as expected?

just plugging in values seems to work for me

hmmmm

i exchange before? to after? in first if and get either a string or empty in logger

seems like a really weird behavior, becaiuse i expect a least false and evaluation of next if (which should return string too)

i for now ended up with (if (t/before? (t/now) (f/parse iso-8601 starts_at)) "Match scheduled" "Match is over”) — but this doesn’t cover my case

and i want to get to the bottom of it

to gain deeper understanding of how things work in clojure

that doesn't make any sense

(if true (print "a") (if true (print "b") (print "c"))) ;; prints a
(if false (print "a") (if true (print "b") (print "c"))) ;; prints b
(if false (print "a") (if false (print "b") (print "c"))) ;; prints c

that's as basic as it gets

do two things in your else case, for illustration purposes

yep, sec

if you print the values you'r comparing (after parsing), are they the same type as t/now?

they are #object[org.joda.time.DateTime 0x1fbd558d "2016-02-07T15:30:00.000Z”]

about else — are there even at all else in clojure?

i can’t find reference

(if (t/before? (t/now) (f/parse iso-8601 starts_at)) "Match scheduled" "Match is over”)

this works as expected

if(test) { return x; } else { return y; } in clojure translates to (if test x y)

yep, this is how i understand it (and appreciate 😅 )

this returns nothing to logger

(if (t/before? (t/now) (f/parse iso-8601 starts_at)) "Match scheduled"
                          ((t/after? (t/now) (f/parse iso-8601 ends_at)) "Match is in progress"
                          "Match is over”))

:thinking_face:

you have an extra wrapping paren?

on the second line

or is that a missing if

yea you forgot the if

yes thank you

but surprisingly

result is the same

so i got and empy res with this too

(if (t/before? (t/now) (f/parse iso-8601 starts_at)) "Match scheduled"
                          (if (t/after? (t/now) (f/parse iso-8601 ends_at)) "Match is in progress"
                          "Match is over”))

mystery.

Empty result? You’re getting nil when you run that code? I don’t see how that’s possible because all paths return a string.

yea...

are you writing this stuff directly into a repl as is, with preset values?

and making sure that each inner expression evaluates as you expect it would?

thank you, i’ll try this in repl (probably should do it all of the time before asking)

@olegakbarov, always ask if you want. There’s no judgement here. I’m pretty good at Clojure and I hang out here because I help when I can and I end up learning a lot too. It’s a good thing.

Yeah, I like actually knowing the answer sometimes 😄