Goals: Add links that are reasonable and good explanations of how stuff works. No hype and no vendor content if possible. Practical first-hand accounts of models in prod eagerly sought.
Picking the right architecture = Picking the right battles + Managing trade-offs
- Clarify and agree on the scope of the system
- User cases (description of sequences of events that, taken together, lead to a system doing something useful)
- Who is going to use it?
- How are they going to use it?
Latency Comparison Numbers (~2012) | |
---------------------------------- | |
L1 cache reference 0.5 ns | |
Branch mispredict 5 ns | |
L2 cache reference 7 ns 14x L1 cache | |
Mutex lock/unlock 25 ns | |
Main memory reference 100 ns 20x L2 cache, 200x L1 cache | |
Compress 1K bytes with Zippy 3,000 ns 3 us | |
Send 1K bytes over 1 Gbps network 10,000 ns 10 us | |
Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD |
A list of commonly asked questions, design decisions, reasons why Clojure is the way it is as they were answered directly by Rich (even when from many years ago, those answers are pretty much valid today!). Feel free to point friends and colleagues here next time they ask (again). Answers are pasted verbatim (I've made small adjustments for readibility, but never changed a sentence) from mailing lists, articles, chats.
How to use:
- The link in the table of content jumps at the copy of the answer on this page.
- The link on the answer itself points back at the original post.
Internet connection and DNS routing are broken from WSL2 instances, when some VPNs are active.
The root cause seems to be that WSL2 and the VPN use the same IP address block, and the VPN routing clobbers WSL2's network routing.
This problem is tracked in multiple microsoft/WSL issues including, but not limited to:
;; Now, replace the loop by more telling operations. | |
(defn tarjan | |
"Returns the strongly connected components of a graph specified by its nodes | |
and a successor function succs from node to nodes. | |
The used algorithm is Tarjan's one." | |
[nodes succs] | |
(letfn [(sc [env node] | |
; env is a map from nodes to stack length or nil, nil means the node is known to belong to another SCC | |
; there are two special keys: ::stack for the current stack and ::sccs for the current set of SCCs |
- Abramsky and Jung "Domain Theory" http://www.cs.bham.ac.uk/~axj/pub/papers/handy1.pdf
- Appel, Andrew "Modern Compiler Implementation in ML"
- Cousot, Patrick "Abstract Interpretation Based Formal Methods and Future Challenges" http://www.di.ens.fr/~cousot/publications.www/Cousot-LNCS2000-sv-sb.pdf
- Darais, Might, and Van Horn "Galois Transformers and Modular Abstract Interpreters" http://arxiv.org/pdf/1411.3962v1.pdf
- Davey and Priestley, "Introduction To Lattices and Order"
- Friedman and Mendhekar, "Using an Abstracted Interpreter to Understand Abstract Interpretation" http://www.cs.indiana.*du/l/www/classes/b621/abiall.pdf
- Friedman and Wand, "Essentials of Programming Languages"
- Jones and Nielson, "Abstract Interpretation: a Semantics-Based Tool for Program Analysis" http://se.inf.ethz.ch/courses/2014b_fall/sv/reading/jones-nielson.pdf
- Livshits, Sridharan, Smaragdakis, et. al. "In Defense of Soundiness: A Manifesto" http://cgi.di.uoa.gr/~smaragd/Soundiness-CACM.pdf
- Might, Matt "Writing an inte
Recent improvements to the ClojureScript compiler have greatly simplified setting up development versus production outputs.
This example uses Figwheel as something that you want to exclude for production, but the pattern is general.
With this simple setup you only need one html file/view and it will work for developement and production.
(ns net.cgrand.decay | |
"Exponentially decaying lists. See http://awelonblue.wordpress.com/2013/01/24/exponential-decay-of-history-improved/ | |
for background and http://clj-me.cgrand.net/2013/02/12/decaying-lists-log-scale-for-lists/ for documentation") | |
;; PRNG, formulas straight from java.util.Random javadoc | |
(defn- seed ^long [^long n] | |
(bit-and (unchecked-multiply n 0x5DEECE66D) | |
(unchecked-dec (bit-shift-left 1 48)))) | |
(defn- next-seed ^long [^long seed] |