I’m tinkering with Oz a Clojure viz library https://github.com/metasoarous/oz and just following the steps in the README, but when I try and render my first viz nothing loads, when I inspect the console in Chrome I see this: Error: Invalid field type "undefined". at qi (oz.js:28) at Ii (oz.js:28) at oz.js:28 at hp (oz.js:28) at new wp (oz.js:28) at jp (oz.js:28) at Object.e.compile (oz.js:28) at CB (oz.js:1205) at Object.<anonymous> (oz.js:1206) at Object.<anonymous> (oz.js:823) my code:

(ns learning-clojure.viz
  (:require [oz.core :as oz]))

(oz/start-server!)


(defn play-data [& names]
  (for [n names
        i (range 20)]
    {:time i :item n :quantity (+ (Math/pow (* i (count n)) 0.8) (rand-int (count n)))}))

(def line-plot
  {:data {:values (play-data "monkey" "slipper" "broom")}
   :encoding {:x {:field "time"}
              :y {:field "quantity"}
              :color {:field "item" :type "nominal"}}
   :mark "line"})

;; Render the plot
(oz/view! line-plot) 

Figured out the issue, the :field needs a :type value set otherwise it breaks

@glfinn83 Calva has a command for loading those tools into the REPL. Don't know if you knew.

This might be useful to beginners: https://github.com/porkostomus/4bb It's 4clojure but as a clojure / babashka script, so you can run it locally.

i have a keymap utility i’m rewriting in Clojurescript, wondering if there’s a better way to write this function:

function concatModifierKeyNames(_k: string, mods: ModifierMap) {
  let k = _k.slice()
  if (mods.alt) k = `Alt+${k}`
  if (mods.ctrl) k = `Ctrl+${k}`
  if (mods.meta) k = `Meta+${k}`
  if (mods.shift) k = `Shift+${k}`
  return k}

(defn concat-modifier-keynames [k mods]
  (let [k (if (:alt mods) (str "Alt+" k) k)
        k (if (:ctrl mods) (str "Ctrl+" k) k)
        k (if (:meta mods) (str "Meta+" k) k)
        k (if (:shift mods) (str "Shift+" k) k)]
    k))

@alidcastano do the modifiers have to appear in a certain order?

@alidcastano One thing that may help is that str will ignore nil values, and when returns nil when the condition is false.

(str (when (= 1 2) "not true") 
     (when (= 1 1) " is true") 
     (when true " always"))
=> " is true always"

I would probably use cond->>:

(defn concat-modifier-keynames [k {:keys [alt ctrl meta shift]}]
  (cond->> k
    alt (str "Alt+")
    ctrl (str "Ctrl+")
    meta (str "Meta+")
    shift (str "Shift+")))

I'm struggling to understand how to iterate across a collection of maps. If I have a simple structure then I can use destructuring. So:

(def map2 {:name "Molly", :species "cat", :colour "grey", :age 9} )
(let [{:keys [age species]} map2] (print age species)) ;;=> 9 cat

(def animals [{:name "Molly" :species "cat", :colour "grey", :age 9}
              {:name "Jack" :species "cat" :colour "ginger" :age 8}]

(defn current_animals [animals]
    (map
        #(
            [{:keys [age species]} %]
        ) animals))

In a book I'm reading it says that cons returns a 'logical' list, a sequence (not a list). Which exact implementation of ISeq is being returned?