| Andrew Cooke | Contents | Latest | RSS | Twitter | Previous | Next

C[omp]ute

Welcome to my blog, which was once a mailing list of the same name and is still generated by mail. Please reply via the "comment" links.

Always interested in offers/projects/new ideas. Eclectic experience in fields like: numerical computing; Python web; Java enterprise; functional languages; GPGPU; SQL databases; etc. Based in Santiago, Chile; telecommute worldwide. CV; email.

Personal Projects

Lepl parser for Python.

Colorless Green.

Photography around Santiago.

SVG experiment.

Professional Portfolio

Calibration of seismometers.

Data access via web services.

Cache rewrite.

Extending OpenSSH.

Last 100 entries

Mapa de Ciclovias en Santiago; How Unreliable is UDP?; SE Santiago 20m Bike Route; Cameron's Rap; Configuring libxml with Eclipse; Reducing Combinatorial Complexity With Occam - AI; Sentidos Comunes (Chilean Online Magazine); Hilary Mantel: The Assassination of Margaret Thatcher - August 6th 1983; NSA Interceptng Gmail During Delivery; General IIR Filters; What's happening with Scala?; Interesting (But Largely Illegible) Typeface; Retiring Essentialism; Poorest in UK, Poorest in N Europe; I Want To Be A Redneck!; Reverse Racism; The Lost Art Of Nomography; IBM Data Center (Photo); Interesting Account Of Gamma Hack; The Most Interesting Audiophile In The World; How did the first world war actually end?; Ky - Restaurant Santiago; The Black Dork Lives!; The UN Requires Unaninmous Decisions; LPIR - Steganography in Practice; How I Am 6; Clear Explanation of Verizon / Level 3 / Netflix; Teenage Girls; Formalising NSA Attacks; Switching Brakes (Tektro Hydraulic); Naim NAP 100 (Power Amp); AKG 550 First Impressions; Facebook manipulates emotions (no really); Map Reduce "No Longer Used" At Google; Removing RAID metadata; New Bike (Good Bike Shop, Santiago Chile); Removing APE Tags in Linux; Compiling Python 3.0 With GCC 4.8; Maven is Amazing; Generating Docs from a GitHub Wiki; Modular Shelves; Bash Best Practices; Good Emergency Gasfiter (Santiago, Chile); Readings in Recent Architecture; Roger Casement; Integrated Information Theory (Or Not); Possibly undefined macro AC_ENABLE_SHARED; Update on Charges; Sunburst Visualisation; Spectral Embeddings (Distances -> Coordinates); Introduction to Causality; Filtering To Help Colour-Blindness; ASUS 1015E-DS02 Too; Ready Player One; Writing Clear, Fast Julia Code; List of LatAm Novels; Running (for women); Building a Jenkins Plugin and a Jar (for Command Line use); Headphone Test Recordings; Causal Consistency; The Quest for Randomness; Chat Wars; Real-life Financial Co Without ACID Database...; Flexible Muscle-Based Locomotion for Bipedal Creatures; SQL Performance Explained; The Little Manual of API Design; Multiple Word Sizes; CRC - Next Steps; FizzBuzz; Update on CRCs; Decent Links / Discussion Community; Automated Reasoning About LLVM Optimizations and Undefined Behavior; A Painless Guide To CRC Error Detection Algorithms; Tests in Julia; Dave Eggers: what's so funny about peace, love and Starship?; Cello - High Level C Programming; autoreconf needs tar; Will Self Goes To Heathrow; Top 5 BioInformatics Papers; Vasovagal Response; Good Food in Vina; Chilean Drug Criminals Use Subsitution Cipher; Adrenaline; Stiglitz on the Impact of Technology; Why Not; How I Am 5; Lenovo X240 OpenSuse 13.1; NSA and GCHQ - Psychological Trolls; Finite Fields in Julia (Defining Your Own Number Type); Julian Assange; Starting Qemu on OpenSuse; Noisy GAs/TMs; Venezuela; Reinstalling GRUB with EFI; Instructions For Disabling KDE Indexing; Evolving Speakers; Changing Salt Size in Simple Crypt 3.0.0; Logarithmic Map (Moved); More Info; Words Found in Voynich Manuscript; An Inventory Of 3D Space-Filling Curves

© 2006-2013 Andrew Cooke (site) / post authors (content).

Y Combinators and Monads - How?

From: "andrew cooke" <andrew@...>

Date: Wed, 2 May 2007 13:38:17 -0400 (CLT)

Search for "unix pipe erlang" and it seems like everyone and their dog has
written code something like that below (they allows functions to be
chained together as parallel processes).

But what if my functions need to manage some state?  I have a rather large
(and useful) (quasi-)monad library.  How do I integrate that?

Andrew

PS "Response" doesn't make much sense out of context, but provides some
information for logging.

-module(chain).

-import(choopa_util, [res_info/2, res_info/3]).
-export([new_end/3, new_link/4, echo/2]).


bootstrap(Fun) ->
    Pid = spawn(fun() -> Fun(Fun) end),
    fun(Message) -> Pid ! Message end.

new_end(Response, Filter, Name) ->
    bootstrap(fun(Self) ->
                      receive
                          {data, Data} ->
                              Filter(Data),
                              Self(Self);
                          exit ->
                              res_info(Response, "Exiting ~s", [Name]);
                          Other ->
                              res_info(Response, "~s: unexpected ~p ",
                                       [Name, Other]),
                              Self(Self)
                      end
              end).

new_link(Response, Filter, Name, Next) ->
    bootstrap(fun(Self) ->
                      receive
                          {data, Data} ->
                              Next({data, Filter(Data)}),
                              Self(Self);
                          exit ->
                              Next(exit),
                              res_info(Response, "Exiting ~s", [Name]);
                          Other ->
                              res_info(Response, "~s: unexpected ~p ",
                                       [Name, Other]),
                              Self(Self)
                      end
              end).

echo(Response, Tag) ->
    fun(Message) -> res_info(Response, Tag),
                    Message
    end.

Bananas etc

From: "andrew cooke" <andrew@...>

Date: Wed, 2 May 2007 13:45:56 -0400 (CLT)

Some answers after sleeping on this (original post was sent yesterday;
reposted today due to svn shenanigans - not having a very good day,
svn-wise).

1 - What I keep calling monads are really bananas and folds and all that
stuff - ana-thing and cata-wotsist - and I really need to get those clear
(and their relation to monads).  For example, the most popular of my
"monad" functions is really a fold that cleans up after a A -> B -> (C *
A) converts [B] to [C] (and what is that thing called? - it's the A that
is my "monad").

2 - This is kind-of irrelevant to what I was stuck on because the levels
are different.  My monads/folds/whatevers are processing (individual items
in) lists of data, while the processes are processing (passing around)
chunks of data (sub-lists).

3 - (2) is kind-of related to streams and protocols.  Working on Mule has
made me more interested in how you define and separate protocols at
different layers (in theory easy, but in practice you seem to need to make
certain compromises).

Andrew

Comment on this post