(Disclaimer: I am a C# guy. I've just started learning Clojure.) I understand that a Clojure program has the ability to manipulate itself or easily generate other programs. It has something to do with everything in Clojure being a data structure and that generating programs would be the same as creating any other type of data structure....
I'm trying to extend JButton with Clojure, but I ran into a problem when I try to create my own constructors. Whenever I use :constructors with :gen-class I keep getting a "ClassFormatError: Duplicate field name&signature" message when I try to instantiate my class. I think I'm following the Clojure docs properly. Am I doing something ...
I'm working with a messaging toolkit (it happens to be Spread but I don't know that the details matter). Receiving messages from this toolkit requires some boilerplate: Create a connection to the daemon. Join a group. Receive one or more messages. Leave the group. Disconnect from the daemon. Following some idioms that I've seen used ...
Sorry if this is a bit of a noob question but I am still getting used to functional programming. I want to write a simple Sudoku solver as an exercise. One of my plans is to create a JTable with 9 rows and 9 columns and initialize them all with the string "123456789" as a starting position. If I have a TableModel I can define a functi...
Currently I'm trying to create sample Wicket page with Clojure (in existing wicket project). Code looks like this: (ns a.set.of.packages.dataview.info.EmptyNodeInfo2Panel (:import [a.set.of.packages.tree TreeModelBean] [a.set.of.packages.dataview.supplemental GenericHeaderPanel])) (gen-class :name a.set.of.packages.dat...
I am not to Clojure and attempting to figure out how to do this. I want to create a new hash-map that for a subset of the keys in the hash-map applies a function to the elements. What is the best way to do this? (let [my-map {:hello "World" :try "This" :foo "bar"}] (println (doToMap my-map [:hello :foo] (fn [k] (.toUpperCase k))...
I have a group of numeric functions in Clojure that I want to validate the arguments for. There are numerous types of arguments expected by the functions, such as positive integers, percentages, sequences of numbers, sequences of non-zero numbers, and so on. I can validate the arguments to any individual function by: Writing validation...
I tried the following in Clojure, expecting to have the class of a non-lazy sequence returned: (.getClass (doall (take 3 (repeatedly rand)))) However, this still returns clojure.lang.LazySeq. My guess is that doall does evaluate the entire sequence, but returns the original sequence as it's still useful for memoization. So what is t...
The Clojure API describes these two functions as: (send a f & args) - Dispatch an action to an agent. Returns the agent immediately. Subsequently, in a thread from a thread pool, the state of the agent will be set to the value of: (apply action-fn state-of-agent args) and (send-off a f & args) - Dispatch a potentially blocking...
Say i have a function that takes to coordinates, x and y. For x I have a sequence of values say [1 2 3] and for y I have another sequence of values say [4 5 6]. How would I get a list with all the combinations of these? So the desired result would be something like: (myfn [1 2 3] [4 5 6]) => [[1 4] [1 5] [1 6] [2 4] [2 5] [2 6] [3 4]...
Say I have a vector: (def data ["Hello" "World" "Test" "This"]) And I want to populate a table somewhere that has an api: (defn setCell [row col value] (some code here)) Then what is the best way to get the following calls to happen: (setCell 0 0 "Hello") (setCell 0 1 "World") (setCell 0 2 "Test") (setCell 0 3 "This") I foun...
I have a function that is supposed to take a lazy seq and return an unrealized lazy seq. Now I want to write a unit test (in test-is btw) to make sure that the result is an unrealized lazy sequence. ...
I've been caught up in long running computations lately thanks to Project Euler and I'd like to know how to abort an evaluation and return to the REPL prompt. I'm running the standard Clojure Box version of Emacs. I tried the obvious REPL > Interrupt Lisp Process and Slime > Interrupt Command but neither kill the execution and return my ...
I have a set of 52 or so latitude/longitude pairs. I simply need to find the shortest path through all of them; it doesn't matter where staring point or ending point is. I've implemented Dijkstra's algorithm by hand multiple times before and don't really have the time to do it again. I've found a couple things that come close, but most...
Where is it already being used in production and how ? ...
What am i doing wrong? Simple recursion of few thousand deep throws "StackOverflowError" If the limit of Clojure recursions is so low, how can I rely on it ? (defn fact[x] (if (<= x 1) 1 (* x (fact (- x 1)) ))) user=> (fact 2) 2 user=> (fact 4) 24 user=> (fact 4000) java.lang.StackOverflowError (NO_SOURCE_FILE:0) ...
I have a java.util.HashMap object m (a return value from a call to Java code) and I'd like to get a new map with an additional key-value pair. If m were a Clojure map, I could use: (assoc m "key" "value") But trying that on a HashMap gives: java.lang.ClassCastException: java.util.HashMap cannot be cast to clojure.lang.Associative No...
I've written a small Swing App before in Clojure and now I'd like to create an Ajax-style Web-App. Compojure looks like the best choice right now, so that's what I'm going to try out. I'd like to have a real tiny edit/try feedback-loop, so I'd prefer not to restart the web server after each small change I do. What's the best way to a...
What are the technical questions I simply must have answers for before I approach someone about introducing a new language? I'm looking for the list of technical questions that without a really good answer, I should not even waste anyone's time by proposing that we use language X. PS: (def X clojure) ...
I thought the whole idea was to have only computation with NO state and NO side effects. Now if a Clojure app(or even worse, a reusable Clojure library ) can use and create any Java object, how can I be sure I don't get side effects or state ? ...