Stack Overflow


Why does (peek (seq [1])) result in: ClassCastException clojure.lang.PersistentVector$ChunkedSeq cannot be cast to clojure.lang.IPersistentStack clojure.lang.RT.peek ( Peek documentation "For a list or queue, same as first, for a vector, same as, but much more efficient than, last. If the collection is empty, returns

I'm working on problems at in Clojure. There is a particular problem that my code doesn't seem to work for. The problem is: ================================== The sequence of triangle numbers is generated by adding the natural numbers. So the 7th triangle number would be 1 + 2 + 3 + 4 + 5 + 6 + 7 =

Hi all, I'm having a problem where a definline'd function is not working when used as a predicate for filtering. It seems to work sporadically - occasionally it works, occasionally it doesn't. I'm thinking it's probably a compile problem since it seems to work or not work consistently for each compile

At Factual, we build and constantly refine a canonical index of real world entities: businesses, locations, and products [1]. We also provide ways for other data to be resolved against our index [2] [3], allowing our service to act as a join table for real-world entities, breaking down barriers between otherwise siloed data.

Hi, Recently I found myself searching for a white space which got lost somewhere between reading an XML file and presenting some results from that via a little webapp. I think, I could track it down to the following example: user> (clojure.pprint/pprint ( (clojure.xml/parse

Potemkin [1] is a collection of facades and utilities that I've found helpful when writing larger-scale libraries or applications. I've never formally announced it before, but I think it's gotten to the point where others can benefit from it. A few highlights: * 'def-map-type', which allows for the definition of custom map-like

Hi again, quick question: Is it at all possible to extend a protocol to a particular primitive array type but also handle nesting of arrays? A double[] is not the same class as double[][] which in turn is not the same Class as double[][][] etc etc and there is no interface tying them together.... So this means

Hi All, I saw a nice summation of software project estimation and thought some of you might like to view it: [link] Enjoy! Alan Thompson

Hi, I implemented small macro to catch multiple exception classes with one body. [link] What do you think? Are there better ways to achieve similar results? Thanks!

It strikes me as a wart, albeit one that won't be much encountered, that there's no good way to discriminate between the user-defined function "catch" and the exception-catching magic symbol "catch" here: user> (defn kick [& o] (apply println "kick the" o)) user> (defn catch [& o] (apply println "catch the" o))


In approximately 20 minutes I begin my first day at Cognitect as a <there are no titles>. These are exciting times for me because it means1 that I can contribute more directly with the evolution of Clojure, ClojureScript, Pedestal and Datomic. For the past year and a half I have used these tools (not so […]

Should you create a new library? :F

On January 20, 2014 the world lost hacker named Timothy Hart. Hart was not just any hacker — he was a hacker of the highest order. If you’ve read more than three books on Lisp then you might have seen his name pop up here and there. If not, then you have definitely felt his […]

The title of this post is intentionally misleading. Kris Burm, for those of you unfamiliar with him, is a game designer1 responsible for a highly praised series of abstract strategy games called Project GIFP. In an interview given circa 2000 Burm describes the challenges of game designers like himself who create purely thinking games without […]

Great things and people that I discovered, learned, read, met, etc. in 2013. No particular ordering is implied. Not everything is new. also: see the lists from 2012, 2011 and 2010 Great blog posts read My favorite Erlang program — When Joe Armstrong blogs about his favorite Erlang program, you read it. There is no […]

I love Kurt Vonnegut. Everything that I’ve read that he’s written is a gem1 and his interviews are amazing. Except for PG Wodehouse, I consider Vonnegut the greatest writer of comedic depth-psychology in the history of the universe. I read very few biographies, but when I learned of the Vonnegut biography And So It Goes, […]

I’ve come to the wonderful world of board and card gaming fairly late in life. While many people were spending days and nights playing Axis & Allies or Egyptian Ratscrew during their formative years I spent my time either building little computer games, riding my skateboard or reading. Growing up I rarely, if ever played […]

The 1st law of thermo-dumb-antics1 states that in a buzzword-riddled startup landscape all disruption cancels out to form a mediocrity. The 2nd law of thermo-dumb-antics describes a condition where the brainpower in a pitch meeting dissipates as heat rather than as good ideas. The 3rd law of thermo-dumb-antics states that if marketing material mentions the […]

One of my favorite talks at last month’s Strange Loop conference was Martin Odersky‘s keynote entitled “The Trouble With Types.” There were many interesting points made in his talk, some that I agree with and some not. However, I’d like to focus in on a very small, seemingly throwaway statement made by Dr. Odersky that […]

I don’t know much about this, but… The learning process is something you can incite, literally incite, like a riot. – Audre Lorde …I can learn more.1 And so can you. 2 Overview Unlocking the Clubhouse by Jane Margolis and Allan Fisher The Brogrammer Effect: Women Are a Small (and Shrinking) Share of Computer Workers […]


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