clojureclojurescriptedn

Can't eval/load-string clojure function from string


I need to read a clojure function from an edn file which outputs hiccup to generate html content. But I'm stuck at the part where the function needs to be evaluated. I receive the error message:

java.lang.RuntimeException: Unable to resolve symbol: fn in this context, compiling:(null:1:1)

((eval (read-string "(fn [] (list [:div\"Hello\"]))")))

and

((load-string "(fn [] (list [:div\"Hello\"]))"))

are working inside a clojure REPL and output the expected result

([:div "Hello"])

project.clj

(defproject infocenter "0.1.0-SNAPSHOT"
  :dependencies [[org.clojure/clojure "1.8.0"]
                 [org.clojure/clojurescript "1.9.225"]
                 [hiccup "1.0.5"]]
  :plugins [[lein-figwheel "0.5.4-7"]]
  :clean-targets ^{:protect false} [:target-path "out" "resources/public/cljs"]
  :cljsbuild {
              :builds [{:id "dev"
                        :source-paths ["src"]
                        :figwheel true
                        :compiler {:main "templ.core"
                                   :asset-path "cljs/out"
                                   :output-to  "resources/public/cljs/main.js"
                                   :output-dir "resources/public/cljs/out"}}]}
  :figwheel {
             :css-dirs ["resources/public/template"]})

core.cljs

(ns templ.core
  (:require-macros [templ.edn :refer [read-edn]]))
(let [div (. js/document getElementById "content")]
     (set! (. div -innerHTML) (read-edn "fn.edn")))

edn.clj

(ns templ.edn
  (:use [hiccup core form]))

(defmacro read-edn
  "Read template from file in resources/"
  [edn-name]
  ;(slurp edn-name)
  ;((eval (read-string "(fn [] (list [:div\"Hello\"]))")))
  ((load-string "(fn [] (list [:div\"Hello\"]))"))
  )


Solution

  • Try this:

    (ns xyz.core
      (:gen-class))
    
    (defn -main
      "I don't do a whole lot ... yet."
      [& args]
      (println "main - enter")
      (println (eval '(+ 2 3)))
      (println ((eval (read-string "(fn [] (list [:div\"Hello\"]))"))))
      (println "main - exit")
    )
    

    with results:

    > lein run
    main - enter
    5
    ([:div Hello])
    main - exit
    

    This is just plain Clojure, and I see you are using CLJS as well. There may be some problem in your setup with the CLJS part of it. What are you trying to do with read-edn and fn.edn? I would avoid macros completely whenever possible.