I'm trying to learn and tool up for a core.logic project. I've found good resources for learning the highlights of some parts. Am I missing some central source for learning all of it?

have you used similar logic programming systems (like prolog) before? I learned prolog in college but you can pretty much learn prolog stuff and apply it directly to core.logic, it's mainly just syntactical differences AFAIK.

@roelofw I wasn't able to require the module from the repl, but it started working automatically later on.

@akiroz I've read some prolog/logic examples and have an idea for how I hope things work. I work for a university; and I'm building something to prove whether our majors can be completed in 4 years with a given plan of course offerings. I imagine I'll be using the simple database stuff a bit. (prerequisite class-1 class-2), etc. It's going to get complicated.

Nice! course registration at my uni was horrible and I could never register for the courses I wanted to take because of timetable/prerequisite issues..... to top it off, the online system is this super slow/buggy Java + OracleDB thing. Ughh...

@roelofw I tried out your code this morning and this works fine:

(defn read-data-painting2
  "Reads the title, description, date , collection, colors and url of a image"
  [id]
  (let [art-objects (-> (str "" id "?key=14OGzuak&format=json&type=schilderij&toppieces=True")
                        (client/get {:as :json})
                        :body
                        :artObject)
        name        (-> art-objects
                        :principalMakers
                        first
                        :name)
        description (:description art-objects)
        date (get-in art-objects [:dating :year])
        collectie (first (:objectCollection art-objects))
        colors (:colors art-objects)]

    {:id id :name name :description description :date date :collectie collectie :colors colors}))

(read-data-painting2 "SK-A-1718")

It returns:

{:id "SK-A-1718",
 :name "Hendrick Avercamp",
 :description
 "Winterlandschap met ijsvermaak. Dorpsgezicht met vele figuren op het ijs: schaatsers, kolfspelers, wandelaars. Rechts een arrenslede, links een kerk.",
 :date 1608,
 :collectie "schilderijen",
 :colors ["#B0AD92" " #64614A" " #D7D3BA" " #76806F" " #373B30" " #1F1C15" " #9E824E"]}

I think in one version of the code you had an additional line in the let: painter (get-in name [:name]) and you had {:id id :name painter :description description :date date :collectie collectie :colors colors} being returned.

that returned nil for :name as name is just a string already so you can't call get-in on it

I see this as output on my webpage :

{:id"SK-A-2963", 
  :name #object[clojure.core$name 0x96b47c "clojure.core$name@96b47c"], 
  :description "Portret van Don Ramón Satué. Lid van de Sala de Alcaldes de Corte per la Audiencia Territorial de Madrid. Heupstuk, naar links, staande met de handen in de zakken.", 
  :date 1823, 
  :collectie "schilderijen", 
  :colors ["#322318" " #0F0E09" " #573525" " #764736" " #796956" " #9F947C" " #BDB89D"], 
  } 

so name does again return a object instead of a name

@agile_geek

Which version do you use. IM on clojure 1.8.0

Shame - but there's never been anything magical about :name keyword. I am testing this just in a normal repl so I'm not serialising it for web but even so the name is just a String so it shouldn't have a problem. I suspect something else is going on. Try calling your fn in a REPL like I did above (read-data-painting "SK-A-1718")

Then it's working well

very very wierd, @agile_geek

So something else is going on. It looks like something is evaluating name symbol as the name fn

Then I think there are two places where things are happing with the output :

(defn homepage [req] (render-file "home.html" {:paintings (api/do-both-in-parallel(api/read-numbers)) } ))

and here :

{% for data  in  paintings %}
   {{ data }} </br> </br>
{% endfor %}  

do-both in parallel does this :

(defn do-both-in-parallel [ids]
  (let [paint-thread (future (pmap read-data-painting ids))
        image-thread (future (pmap read-image-url ids))]
    (pmap merge @paint-thread @image-thread)))  

so its making the big seq of maps with al the data I want

So I can't see anything obviously wrong. I have said this before but using map for side effects like making an http call like you are doing here is bad practice as it sometimes means that the side effect never happens so we tend to force realisation using something like doall but if this was the problem you would see no data at all in the response.

oke, I use pmap because I want to work as much as possible with the api calls. Otherwise it takes long to display things. Some 7 seconds

I understand that and it's not the problem you are seeing.

There's some odd behaviour here as what's happening is that the name function is being returned instead of the value of the name var bound in your let. This may be some side effect of all the async threads you are using as as well as pmap you are using future but I think you may have found a bug. Either way shadowing a fn's name is bad practice in def let or argument vectors so I would just change your symbol used in the let to painter or painter-name as you did.

If you have the entire code base somewhere you can share it, like on github, I can take a longer look sometime but it won't be for a while.

@agile_geek I can put it into github or bitbucket

and it's no problem that it takes a while. I have a working code so I can continue on

Github would be good. Make sure it's the entire codebase incuding all the resources, project.clj etc. i.e. push the root project directory

oke, I did experiment again and when I change :name to :painter everything works well

Stick with that for now but push the code you have so I can try it out.

That is strange. I tested your code, and that is work fine at me too. Please share with me what is the problem.. because I work on rest-api too. (like a beginner)

The code can be found here : https://github.com/rwobben/paintings

@sb : I do not work with rest-api but with clj-http

I use cheshire

I think, similar ok. I don’t know which faster, maybe clj-http

and the problem is that if I use :name I see a object as output. When rename it to for example : painter everything works well

hmm

I do not have to use cheshire because clj-http can convert json as a clojure object

@agile_geek is the link what you need ?

@roelofw that's fine

@roelofw Ok!

I see the x y parameter wrong (maybe that is true?) (but I really don’t understand what is the main problem.. I don’t have really big experience)

I see at the pic two zero

FYI the #object[clojure.core$name 0x96b47c "clojure.core$name@96b47c"] is telling you that the thing in the map is clojure.core/name which is a Clojure function that takes a String, Symbol or Keyword and returns the String representation of it. https://clojuredocs.org/clojure.core/name

@roelofw found it!

(defn read-image-url
  "Reads the image-url"
  [id]
  (let [art-objects (-> (str "" id "/tiles?key=14OGzuak&format=json")
                        (client/get {:as :json})
                        :body
                        :levels
                        )

        url (filter #(= (:name %) "z4") art-objects)
        tiles (:tiles (first url))
         ]
    {:id id :name name :tiles tiles}))

You merge the results of read-image-url with the results of read-data-painting

here:

(defn do-both-in-parallel [ids]
  (let [paint-thread (future (pmap read-data-painting ids))
        image-thread (future (pmap read-image-url ids))]
    (pmap merge @paint-thread @image-thread)))

yes , image-url takes care of the tiles part. read-data takes care of the rest of the output

As the @image-thread maps coming back from read-image-url is last it's :name value overwrites any :name from read-data-painting

so you always get the :name from the call to read-image-url

look at the way you construct name in read-image-url

where is the value on name set?

yes, im filtering on the items where name : z4

not that

where do you assign a value to the name symbol in the let?

in the other function as I understand where you are going to

you set art-objects, url and tiles but no name

so when you reference name when constructing the map returned from read-image-url you are returning the name function

yes, the name is a part of the json reponse. not data that I want to be the output

But you are referencing a symbol called name without giving it a value in read-image-url

which one makes now the function. the filter one or the -> one

neither

look at the map returned from read-image-url here: {:id id :name name :tiles tiles}

yep, there I use :name

you are setting a key :name with the value from a symbol called name

but you have no value for the symbol name

yep, where name schould be the one in the let of the same function

but there's no name declared in the let in read-image-url do you see?

(let [art-objects (-> (str "" id "/tiles?key=14OGzuak&format=json")
                        (client/get {:as :json})
                        :body
                        :levels
                        )

        url (filter #(= (:name %) "z4") art-objects)
        tiles (:tiles (first url))
         ]
    {:id id :name name :tiles tiles})

nope

name is is only declared in the read-data-url in the let

chips, name schould not be there

I messed up my code

When I delete that part , everything works well

@agile_geek thanks for the time

next challenge : make a own design inspired by this one : http://wedesignthemes.com/html/redart/default/

first I have to look up how to make a picture frame with css that fits all the paintings

@agile_geek any furthers remarks on the code

This is my first projct ever made in clojure

@roelofw no problem. This is how we learn

@agile_geek yes, and we learn from our mistakes not from the things that we can do without any problem

@agile_geek now some html and css work to do , to make a nice layout to show all the images

How can I tell selmer that the styles.css is in the resources folder ; {% style "styles.css" %}

also chancing it to {% style "css/styles.css" %} and putting the css file into resources/css does not make that the css file is found

maybe luminus is a good way for a starting project

https://github.com/yogthos/Selmer#style

@dpsutton still confused. I do now (render "{% style \"/css/screen.css\" %}"

and now I see render " " on my screen

I'm not sure. I've never used selmer

just pointing you to the documentation in case you hadn't seen it

What do you use then ?

I thought selmer was a easy choice but im fighting all the way now

Selmer is easy. The style tag just makes it easy to link to css. You need to serve your css like normal using ring

#akiroz Was it Elucian Banner perchance? :-)

@dominicm : So I schould so <link rel="stylesheet" type="text/css" href="public/css/styles.css">

nope, still not found 😞

@nathansmutz I'm not sure what the underlaying system is called since they styled it to our uni but... might be~ I only found out about the tech stack when the server returned stacktraces in a 500 response xD

Is there a sort of bare luminus template ?

@roelofw lein new luminus <project-name>

@roelofw can you go to localhost:3000/public/css/styles.css ? If not, that's why it's broke

not found. also 'resources/public/css/styles.css` give a 404 error

So are you serving your public folder? If so, how are you doing it?

I did not change anything in the code. Just placing things into that directory and try to point to it

maybe I can better find a good book/tutorial about web development with only ring and compojure

I know that Home.html is found bu selmer bu just doing ( render 'home.html ..... )

I thought css files are also found that way

someone who can recommend a book ?

I think I already mentioned this one? https://pragprog.com/book/dswdcloj2/web-development-with-clojure-second-edition

is this a book only about luminus or also about making web apps with just compojure

@agile_geek do you have a idea why <link rel="stylesheet" type="text/css" href="/css/style.css"> cannot find a css file which resides in resources/public/css directory ?

I have edition 1 but it covers how to build a simple web app with just ring/compojure not sure about edition 2

re: your second question, depends on how your organising your resources and the routes defined in compojure. Can't tell without code and I'm at work in middle of another issue atm

oke, NO

NP

This is my handler file with the routes :

(ns paintings.handler
  (:require [compojure.core :refer :all]
            [compojure.route :as route]
            [ring.middleware.defaults :refer [wrap-defaults site-defaults]]
            [paintings.views :as views]
            ))

(defroutes app-routes
  (GET "/" [] views/homepage)
  (route/not-found "Not Found"))

(def app
  (wrap-defaults app-routes site-defaults))  

I have then a home.html in resources and a home.css file in resources/public/css

@roelofw http://safaribooksonline.com/ free in every 14 days 🙂

lot of book there.. I read that books

well, if its not at "/", then you return a 404

so your handler can't possibly return anything but your homepage of 404

oke, so I have to make another entry for the css files and so on , @dpsutton ?

you probably want to serve your public folder

@roelofw you probably need to add a (route/resources "/") to your app-routes

that should serve static routes from your resources folder

oke, I will hit some tutorials where I have to do that

It's been a while since I did this but it probably needs to go after the GET but before the not-found

so something like this :

(defroutes app-routes
  (GET "/" [] views/homepage)
           (route/resources "/")
  (route/not-found "Not Found")) 

Yep although the indentation is a bit strange in that snippet but that's probably just slack

still no luck

you probably need to check that the reference in the html is correct too..it's been a while since I did this from scratch and I can't remember what the path to resources is relative too.

find an example somewhere

I m a little bit further. Can selmer work with html5

I think so

I have this template now :

<!doctype html>

<html lang="en">
<head>
   <meta charset="utf-8">

   <title>The HTML5 Herald</title>
   <meta name="description" content="The HTML5 Herald">
   <meta name="author" content="SitePoint">

    <link rel="stylesheet" type="text/css" href="/css/styles.css">

   <!--[if lt IE 9]>
   <script src="https://cdnjs.cloudflare.com/ajax/libs/html5shiv/3.7.3/html5shiv.js"></script>
   <![endif]-->
</head>

<body>
 <h1> ik wordt gek van clojure</h1>

</body>
</html>
 

and I see two errors on Edge. First the end tag of head is not right

and second it says there are more then 1 body tag

I'd get rid of that IE9 script hack unless you really need it to test...its probably not the problem but it's another thing that can go wrong.

I haven't used Selmer for 3 years so I'm not going to be much help

@agile_geek what do you use then

I work now with selmer for 2 / 3 days and its making me grazy

I see now the background when I putting it into the css folder. crazy

Mostly Reagent and Re-frame to serve single page apps or plain hiccup but I rarely write an app from scratch so this stuff is usually already in place.

oke, maybe I also will try luminus

then I also know that some things are in place

from nothing is one step too far for me

you are doing from nothing right now i think

pity, that I get a lot of libraries with it that I do not need

he means he usually works on existing apps

@dpsutton yep, and so far no fun

@dpsutton Correct I am usually working on something someone else started. Frequently it's a service not a UI as well so it's often just api request/responses

I've written apps from scratch just not for a little while

were you at the conj by any chance?

No I co-organise Clojure eXchange in London which was on at same time

ah. i'll need to watch those videos

was wondering if we had run into each other by any chance but it sounds like we haven't

Nope but maybe next year? 😀

I'm considering going to a US conference but Strange Loop is top of my list

on luminus when I do this : [paintings2.api_get :as api])) does it find the file api_get.clj which resides in src ?

I decided to skip Strange Loop this year and go to the Conj instead (I went to Clojure/West and could only do one more conference). Having gone to Strange Loop four times, as well as several past Clojure/West and Clojure/conj events, I think that was the right decision (for me). If you’ve never been to Strange Loop, it’s definitely worth going at least once — it can be pretty inspirational and the talks are often fascinating — but I find I get more value out of /West and /conj these days.

I use the paintings2.api-get in the directory routes

@roelofw You mean in a (:require …) clause inside (ns …) ?

yes

see here :

(ns paintings2.routes.home
  (:require [paintings2.layout :as layout]
            [compojure.core :refer [defroutes GET]]
            [ring.util.http-response :as response]
            [ :as io]
            [paintings2.api_get :as api]))  

If the (ns …) inside src/paintings2/api_get.clj says paintings2.api-get (which it should), then the :require should match that.

The rule of thumb is: _ in filenames, - in namespaces.

and that is correct, in src there is a file called api-get.clj

The file should be api_get.clj, the namespace should be api-get.

but I see this familiar error : Caused by: java.io.FileNotFoundException: Could not locate paintings2/api_get__init.class or paintings2/api_get.clj on classpath.

If your file is called api-get.clj, that’s wrong.

oke, then I mixed up the rwo

two

Files have underscores. Namespaces have hyphens.

Still errors :

java.lang.Exception: namespace 'paintings2.api-get' not found after loading '/paintings2/api_get'  

(ns paintings2.routes.home
  (:require [paintings2.layout :as layout]
            [compojure.core :refer [defroutes GET]]
            [ring.util.http-response :as response]
            [ :as io]
            [paintings2.api-get :as api]))

(defn home-page []
  (layout/render
    "home.html"  "home.html"  {:paintings (api/do-both-in-parallel(api/read-numbers))  }))

(defroutes home-routes
  (GET "/" [] (home-page)))  

filename : api_get.clj

what did I do wrong

the file has a underscore and the namespace a hypens

or do I need to say which directory the api-get resides

it figures out the directory based on the namespace

so it should be paintings2/api_get.clj

and the file you posted should be in paintings2/routes/home.clj

@jjfine that is all correct

and still the error 😞

does paintings2/api_get.clj look like:

(ns paintings2.api-get ...

if I look at the error , this is somehow wrong : [paintings2.api-get :as api]))

the same as this one : https://github.com/rwobben/paintings/blob/master/src/paintings/api_get.clj

thats the problem

underscore instead of dash

except the ns is this : (ns paintings2.api_get

change it to a dash

the require and the ns need to match

the filename needs a underscore

oke, that part worked

now I see this error : ' java.lang.String cannot be cast to clojure.lang.Associative `

oke, that one is solved also

Now hoping I can get the layout that I wanted now

the same problem. I have a background-image on resources/public/img and a css file on resources/public/css

and when I do background: url(../img/old-wall.jpg) no-repeat center center fixed;

no background to see

anyone a idea how to make this work

@roelofw you need to remove the .. at the start of the image url

resources are served relative to the resources dir

you may need /public/img/old-wall.jpg I can't remember

try with and without public

nope, this background: url('/img/old-wall.jpg') no-repeat center center fixed; is not showing the background

and this is not working also background: url('/public/img/old-wall.jpg') no-repeat center center fixed;

silly question but you do have a file called old-wall.jpg in the directory resources/public/img/?

and you have (routes/resources "/") in the routes def?

Directory of C:\Users\rwobb\Desktop\clojure\paintings2\resources\public\img

05-12-2016  19:45    <DIR>          .
05-12-2016  19:45    <DIR>          ..
05-12-2016  16:24            69.716 old-wall.jpg
               1 File(s)         69.716 bytes
               2 Dir(s)  771.299.135.488 bytes free  

and this is the routes/home.clj file made by lumunis :

(ns paintings2.routes.home
  (:require [paintings2.layout :as layout]
            [compojure.core :refer [defroutes GET]]
            [ring.util.http-response :as response]
            [ :as io]
            [paintings2.api-get :as api]))

(defn home-page []
  (layout/render
    "home.html" {:paintings (api/do-both-in-parallel(api/read-numbers))  }))

(defroutes home-routes
  (GET "/" [] (home-page)))  

so no 'routes/resources "/")` part

Yes that may be it

the css seems to be found now

I think you don't need public in the path

even though the img dir is below public

when I do

(defroutes home-routes
  (GET "/" [] (home-page))
  (routes/resources "/")  )  

I see this error message : No such namespace: routes, compiling:(paintings2/routes/home.clj:14:3)

here the whole route file :

(ns paintings2.routes.home
  (:require [paintings2.layout :as layout]
            [compojure.core :refer [defroutes GET]]
            [ring.util.http-response :as response]
            [ :as io]
            [paintings2.api-get :as api]))

(defn home-page []
  (layout/render
    "home.html" {:paintings (api/do-both-in-parallel(api/read-numbers))  }))

(defroutes home-routes
  (GET "/" [] (home-page))
  (routes/resources "/")  )
 

The (routes/resources "/") is mapping all static resources starting at a path "/" to the default public folder in resources

https://weavejester.github.io/compojure/compojure.route.html#var-resources

my fault

add resoources to the refer vector in the require for compojure like so: [compojure.core :refer [defroutes GET resources]]

then you can just say (resources "/")

Woops

wait

should be this:

[compojure.route :refer [resources]]

as a new line in the :require

and the compojure.core line stays as it was

as resources is defined in compojure.route not compojure.core

what happened to your not-found route?

is there another namespace with routes in it where you've already defined not-found and resources?

I think I'm confusing you because I can only see a small part of your entire code base

nope, I started again with a luminus template

Ah OK

and I think there is no not-found route

No such namespace: routes

must that line not be [compojure.route :refer [routes]]

I have never used liminus so I may be steering you wrong but I think that if you need to serve static files like css and images you need resources route defined and you will need not-found to handle URLs that don't match a route.

Stop fo ra minute while I explain

In a namespace declaration you can bring in libraries using the :require keyword as above

there are several patterns for this

you can give a required namespace an alias like this: [compojure.route :as routes]

the :as will mean I can call a fn in the compojure.route namespace like this (routes/not-found)

I can prefix any fn in the compojure.route namespace with routes and it will find it so I can also say (routes/resources)

Another way to require fn's from a namespace is like this:

[compojure.route :refer [not-found resources]]

this will just require the names fn's

in this case just not-found and resources but nothing else in compojure.route

There is another way to do this which is not recommended which is to require all fn's without a namespace alias or listing them:

[compojure.route :refer :all]

oke, I sometimes see that

So to get both not-found and resources which are both in compjure.route I could do this:

when I use refer , is it right to use not-found like this (not-found) or do I use (clojure.route/not-found) ?

(ns ....
   (:require [compojure.route :as routes])

...
(defroutes app
  (routes/resources "/")
  (routes/not-found))

or

(ns ...
  (:require [compojure.route :refer [not-found resources])

...
(defroutes app
  (resources "/")
  (not-found))

I've left out the GET in the defroutes but you would obviously have that too

Does that make sense?

yes, makes a lot sense

so I did

(defroutes home-routes
  (GET "/" [] (home-page))
  (resources "/")  ) 

but still no background 😞

So you would need the [ ... :refer [...]] version of require

yep

I did that

ns paintings2.routes.home
  (:require [paintings2.layout :as layout]
            [compojure.core :refer [defroutes GET  ]]
            [ring.util.http-response :as response]
            [ :as io]
            [paintings2.api-get :as api]
            [compojure.route :refer [resources]]))

(defn home-page []
  (layout/render
    "home.html" {:paintings (api/do-both-in-parallel(api/read-numbers))  }))

(defroutes home-routes
  (GET "/" [] (home-page))
  (resources "/")  )
 

OK that looks OK so must be something to do with the path in the html template file

I think so

Anyway got to go...good luck

I did a lot of googeling but I did not find any link/tutorial for a background-image

thanks

you don't need a tutorial on background image

you need a tutorial on serving static files

http://www.luminusweb.net/docs#the_resources_directory

follow that tutorial and get the site up and running how they ahve

and then adapt it to your needs afterwards

https://github.com/ring-clojure/ring/wiki/Static-Resources may be of some help.

@dpsutton I did everything according to that tutorial

both css and the img are in the public directory

So I have no idea why the image is not shown