Alson Kemp


Archive for the ‘Programming’ Category

AWS ALB <-> Lambda

without comments

Generally, the tooling around Amazon Web Services’ services is pretty good but the newness of the Application Load Balancer <-> Lambda linkage has been a bit lacking (the linkage is a bit new). Also, we use Typescript and the tooling didn’t support TS very well.

The AWS-Serverless-Express node module was migrated to Vendicia’s Serverless-Express ( and the new maintainer is making rapid progress fixing this up but we were trying to get into production at the same time so went ahead and built a straightforward ALB<->Lambda adapter (heavily borrowing from Serverless-Express). See this GitHub Gist:

Usage is pretty simple: just convert an ALB Request Lamba Event to an Express Request; then convert the Express Response back to an ALB Response Lambda Event.

let app: any;
module.exports.handler = async (event: Lambda.ALBEvent, context: ALBEventRequestContext): Promise&lt;Lambda.ALBResult&gt; =&gt; {
  // Start a server (if one doesn't exist), then memoize it.
  if (!app) {
    app = await __setup();

  const req = alb.fromALBEvent(event); // <-- From ALB to Express
  let resp = new alb.ServerlessResponse(req); // Need to setup a Response for use in the app handle

  return new Promise((resolve, reject) =&gt; {
    app.handle(req, resp); // Have Express handle the request and return the response.
    return alb.waitForStreamComplete(resp).then(() => {
      const albResp = alb.toALBResult(resp, binaryMimeTypes); // <-- From Express to ALB
      return resolve(albResp);
    }).catch((err: any) =&gt; {
      console.err(`HANDLER ERROR: ${err}`);
      return reject(err);

Written by alson

January 21st, 2021 at 10:14 pm

Posted in Programming

Go experiment: de-noising

with 2 comments

CoffeeScript is a great example of how to de-noise a language like Javascript. (Of course, I know people that consider braces to be a good thing, but lots of us consider them noise and prefer significant whitespace, so I’m speaking to those folks.) What would Go code look like with some of CoffeeScript’s denoising?

TL;DR : the answer is that de-noised Go would not look much different than normal Go…

As an experiment, I picked some rules from CoffeeScript and re-wrote the Mandelbrot example from The Computer Benchmarks Game. Note: this is someone else’s original Go code, so I can’t vouch for the quality of the Go code….

Here’s the original Go code:

/* targeting a q6600 system, one cpu worker per core */
const pool = 4

const ZERO float64 = 0
const LIMIT = 2.0
const ITER = 50   // Benchmark parameter
const SIZE = 16000

var rows []byte
var bytesPerRow int

// This func is responsible for rendering a row of pixels,
// and when complete writing it out to the file.

func renderRow(w, h, bytes int, workChan chan int,iter int, finishChan chan bool) {

   var Zr, Zi, Tr, Ti, Cr float64
   var x,i int

   for y := range workChan {

      offset := bytesPerRow * y
      Ci := (2*float64(y)/float64(h) - 1.0)

      for x = 0; x < w; x++ {
         Zr, Zi, Tr, Ti = ZERO, ZERO, ZERO, ZERO
         Cr = (2*float64(x)/float64(w) - 1.5)

         for i = 0; i < iter && Tr+Ti <= LIMIT*LIMIT; i++ {
            Zi = 2*Zr*Zi + Ci
            Zr = Tr - Ti + Cr
            Tr = Zr * Zr
            Ti = Zi * Zi

         // Store the value in the array of ints
         if Tr+Ti <= LIMIT*LIMIT {
            rows[offset+x/8] |= (byte(1) << uint(7-(x%8)))
   /* tell master I'm finished */
   finishChan <- true

My quick de-noising rules are:

  • Eliminate var since it can be inferred.
  • Use ‘:’ instead of const (a la Ruby’s symbols).
  • Eliminate func in favor of ‘-> and variables for functions.
  • Replace braces {} with significant whitespace
  • Replace C-style comments with shell comments “#”
  • Try to leave other spacing along to not fudge on line count
  • Replace simple loops with an “in” and range form

The de-noised Go code:

# targeting a q6600 system, one cpu worker per core
:pool = 4

:ZERO float64 = 0  # These are constants
:LIMIT = 2.0
:ITER = 50   # Benchmark parameter
:SIZE = 16000

rows []byte
bytesPerRow int

# This func is responsible for rendering a row of pixels,
# and when complete writing it out to the file.

renderRow = (w, h, bytes int, workChan chan int,iter int, finishChan chan bool) ->

   Zr, Zi, Tr, Ti, Cr float64
   x,i int

   for y := range workChan
      offset := bytesPerRow * y
      Ci := (2*float64(y)/float64(h) - 1.0)

      for x in [0..w]
         Zr, Zi, Tr, Ti = ZERO, ZERO, ZERO, ZERO
         Cr = (2*float64(x)/float64(w) - 1.5)

         i = 0
         while i++ < iter && Tr+Ti <= LIMIT*LIMIT
            Zi = 2*Zr*Zi + Ci
            Zr = Tr - Ti + Cr
            Tr = Zr * Zr
            Ti = Zi * Zi

         # Store the value in the array of ints
         if Tr+Ti <= LIMIT*LIMIT
            rows[offset+x/8] |= (byte(1) << uint(7-(x%8)))
   # tell master I'm finished
   finishChan <- true

That seems to be a pretty small win in return for a syntax adjustment that does not produce significantly enhanced readability. Some bits are nice: I prefer the significant whitespace, but the braces just aren’t that obtrusive in Go; I do prefer the shell comment style, but it’s not a deal breaker; the simplified loop is nice, but not incredible; eliding “var” is okay, but harms readability given the need to declare the types of some variables; I do prefer the colon for constants. Whereas Coffeescript can dramatically shorten and de-noise a Javascript file, it looks as though Go is already pretty terse.

Obviously, I didn’t deal with all of Go in this experiment, so I’ll look over more of it soon, but Go appears to be quite terse already given its design…

Written by alson

May 13th, 2013 at 11:34 pm

Posted in Programming

[Synthetic] Performance of the Go frontend for GCC

with 8 comments

First, a note: this is a tiny synthetic bench.  It’s not intended to answer the question: is GCCGo a good compiler.  It is intended to answer the question: as someone investigating Go, should I also investigate GCCGo?

While reading some announcements about the impending release of Go 1.1, I noticed that GCC was implementing a Go frontend.  Interesting.  So the benefits of the Go language coupled with the GCC toolchain?  Sounds good.  The benefits of the Go language combing with GCC’s decades of x86 optimization?  Sounds great.

So I grabbed GCCGo and built it.  Instructions here:

Important bits:

  • Definitely follow the instructions to build GCC in a separate directory from the source.
  • My configuration was:

/tmp/gccgo/configure --disable-multilib --enable-languages=c,c++,go

I used the Mandelbrot script from The Benchmarks Game at mandlebrot.go.  Compiled using go and gccgo, respectively:

go build mandel.go
gccgo -v -lpthread -B /tmp/gccgo-build/gcc/ -B /tmp/gccgo-build/lto-plugin/ \
  -B /tmp/gccgo-build/x86_64-unknown-linux-gnu/libgo/ \
  -I /tmp/gccgo-build/x86_64-unknown-linux-gnu/libgo/ \
  -m64 -fgo-relative-import-path=_/home/me/apps/go/bin \
  -o ./mandel.gccgo ./mandel.go -O3

Since I didn’t install GCCGo and after flailing at compiler options for getting “go build” to find includes, libraries, etc, I gave up on the simple “go -compiler” syntax for gccgo. So the above gccgo command is the sausage-making version.

So the two files:

4,532,110 mandel.gccgo  - Compiled in 0.3s
1,877,120 mandel.golang - Compiled in 0.5s

As a HackerNewser noted, stripping the executables could be good. Stripped:

1,605,472 mandel.gccgo
1,308,840 mandel.golang

Note: the stripped GCCGo executables don’t actually work, so take the “stripped” value with a grain of salt for the moment. Bug here.

GCCGo produced an *unstripped* executable 2.5x as large as Go produced. Stripped, the executables were similar, but the GCCGo executable didn’t work. So far the Go compiler is winning.

Performance [on a tiny, synthetic, CPU bound, floating point math dominated program]:

time ./mandel.golang 16000 > /dev/null 

real  0m10.610s
user  0m41.091s
sys  0m0.068s

time ./mandel.gccgo 16000 > /dev/null 

real  0m9.719s
user  0m37.758s
sys  0m0.064s

So GCCGo produces executables that are about 10% faster than does Go, but the executable is nearly 3x the size.  I think I’ll stick with the Go compiler for now, especially since the tooling built into/around Go is very solid.

Additional notes from HN discussion:

  • GCC was 4.8.0.  Go was 1.1rc1.  Both AMD64.

Written by alson

May 5th, 2013 at 2:35 pm

Posted in Programming

Turbinado update

with 2 comments

Turbinado Logo For those of you interested in Turbinado, here’s a quick status update:

  • I separated the code for the website from the code for the framework.  The framework is here and the website code is here.
  • I’m going to finish up implementing HAML templating for Turbinado in the next few days.
  • After HAML templates are in, I’ll provide a tutorial on implementing a mini-CMS/wiki in Turbinado (the code is already in the website.  The standard-Rails-ish “look, Mom!  No code!” type of tutorial.  Just enough to convince you to download it, but not enough to get you to be significantly productive.  😉
  • Adam Stark is providing some greatly needed polish here as he attempts to get this beastie to build.  Turbinado really needs to be easier to build…
  • Diego Echeverri is doing some work to get Turbinado to work with GHC 6.10 here. I had a difficult time getting my HSP-ish View templates working with 6.10, so I hope Diego can do it. I’d greatly prefer to be working with 6.10, but I couldn’t get there…

Writing a little web framework turns out to be a lot of work (it’s all the little stuff (documentation!!) that really gets ya).  I’ve greatly appreciated the ability to build on the work of others (especially Niklas Broberg, Don Stewart, Bjorn Bringert and John Goerzen) and am grateful that others are providing help to this fledgling project.

Written by alson

December 18th, 2008 at 2:13 pm

GitHub, ‘git’ and the forking fallacy

with 3 comments

GitHub is a pretty sweet system. One of the best aspects of _web 2.0_ has been the focus on simple, straightforward web app usability/utility.  GitHub is a great example of some of _web 2.0’s_ best attributes: a really interesting model coupled with straightforward usability and _just a touch_ of AJAX.  I never would have tried Git without GitHub.

Git is pretty interesting, too. Turns out that git is effective at encouraging social involvement in coding. The Turbinado project has been forked a few times… ‘Forked’?! Wait! That’s what happens when projects are in deep trouble, right?!

Maybe so, but not necessarily in git. Since git is a decentralized revision control system (like our beloved darcs), ‘forking’ is roughly equivalent to ‘checking out’. A ‘fork’ is a good thing, so Rails’ fork count (**398**) is **heroic**.

Written by alson

December 18th, 2008 at 1:04 am

Thinking About Haskell*: You Know Lazy Evaluation; You Just Don’t Know It

with 15 comments

[Post updated to reflect comments. …too much late night typing…]
Lazy evaluation is a very novel aspect of Haskell. Turns out that it’s not that difficult to think about.

A very common example of lazy-ish evaluation is ‘&&’ operators used in lots of languages (using C#):

if ( (obj != null) && (obj.someMethod() == somethingElse) ) {
  // do something

Read the rest of this entry »

Written by alson

December 16th, 2008 at 1:33 am

A HAML parser for Haskell

with 2 comments

HAML‘s lovely. As I’ve been working with Turbinado, I’ve been having some issues with HSP. HSP is an insanely impressive piece of software, but its error messages can be a bit unclear. So I started playing around a bit with HAML. Got me wondering “How easy would be to write a HAML parser in Haskell?”

So I tried. Here’s a first-pass, to-be-updated [and somewhat incomplete] HAML parser for Haskell. Not all of the features are implemented, but it’s a start.  It generates HTML bits suitable for compilation by GHC.


f = content

page = #content
         %h2 Welcome to our site!
         %p = print_information
           = print_inline
           = render
         [abba = ding, ding = abba] dinger


f =
    (stringToHtml "content")
page =
       ((tag "div"![strAttr "id" "content"])
         ((tag "div"![strAttr "class" "left column"])
         ((tag "h2")
             (stringToHtml "Welcome to our site!")
         ((tag "p")
            (stringToHtml print_information)
         ((tag "p")
           (stringToHtml print_inline)
         ((tag "div"![strAttr "class" "right column"])
           (stringToHtml render)
         ((tag "div"![strAttr "abba" "ding", strAttr "ding" "abba"])
                                    (stringToHtml "dinger")

le Code

module Main where

import Text.ParserCombinators.Parsec
import Text.ParserCombinators.Parsec.Language
import Text.ParserCombinators.Parsec.Pos
import qualified Text.ParserCombinators.Parsec.Token as T
import Data.Char
import Data.List
import Data.Maybe
import System.IO.Unsafe

main = do s <- getContents
          case (parse mainParser "stdin" s) of
            Left  err -> putStrLn "Error: " >> print err
            Right hs  -> putStrLn hs

-- Try to parse HAML, otherwise re-output raw lines

mainParser = do whiteSpace
                ls <- many1 (hamlCode <|> tilEOL)
                return $ unlines ls
-- * HAML lexer
hamlLexer = T.makeTokenParser emptyDef
whiteSpace= T.whiteSpace hamlLexer
lexeme    = T.lexeme hamlLexer
symbol    = T.symbol hamlLexer
natural   = T.natural hamlLexer
parens    = T.parens hamlLexer
semi      = T.semi hamlLexer
squares   = T.squares hamlLexer
stringLiteral= T.stringLiteral hamlLexer
identifier= T.identifier hamlLexer
reserved  = T.reserved hamlLexer
reservedOp= T.reservedOp hamlLexer
commaSep1 = T.commaSep1 hamlLexer
-- * Main HAML parsers

-- hamlCode is just many identifiers (e.g. 'func a b c' followed by '=' followed by a hamlBlock
-- func a b c = %somehaml
hamlCode = try ( do is <- many1 identifier
                    symbol "="
                    currentPos <- getPosition
                    x <- manyTill1
                          (lexeme $ hamlBlock)
                          (notSameIndent currentPos)
                    return $ (concat $ intersperse " " is) ++
                             " = \n" ++
                             (concat $ (intersperse (indent currentPos ++ "+++\n")  $ filter (not . null) $ x))

-- A Block may start with some whitespace, then has a valid bit of data
hamlBlock   = do currentPos <- getPosition
                 bs <- manyTill1
                      (pTag <|> pText)
                      (notSameIndent currentPos)
                 return $ intercalate (indent currentPos ++ "+++\n") bs

pTag    = do    currentPos <- getPosition
                    (do t  <- lexeme tagParser
                        ts <- (isInline currentPos >> char '/' >> return []) <|>
                        return $ intercalate "\n" $ filter (not . null) $
                          [ (indent currentPos) ++ "((" ++ (if (null ts) then "i" else "") ++ t  ++ ")"
                          , if null ts then [] else ts
                          , (indent currentPos) ++ ")\n"]

pText = lexeme stringParser

notSameIndent p = (eof >> return []) <|>
                  (do innerPos <- getPosition
                      case (sourceColumn p) == (sourceColumn innerPos) of
                                True  -> pzero
                                False -> return []

-- * Various little parsers

tagParser :: CharParser () String
tagParser = do     t <- optionMaybe tagParser'
                   i <- optionMaybe idParser
                   c <- optionMaybe (many1 classParser)
                   a <- optionMaybe attributesParser
                   if (isJust t || isJust i || isJust c || isJust a)
                       do return $ "tag \"" ++ (fromMaybe "div" t) ++ "\"" ++
                           (if not (isJust i || isJust c || isJust a) then "" else
                              concat $
                               [ "!["
                               , intercalate ", " $ filter (not . null)
                                   [ (maybe "" (\i' -> "strAttr \"id\" \"" ++ i' ++ "\"") i)
                                   , (maybe "" (\c' -> "strAttr \"class\" \"" ++ (intercalate " " c') ++ "\"") c)
                                   , (maybe "" (\kv -> intercalate ", " $ map (\(k,v) -> "strAttr \"" ++ k ++ "\" \"" ++ v ++ "\"") kv) a)
                               , "]"]
                     else pzero

tagParser' :: CharParser () String
tagParser' =  do char '%'
                 many1 termChar

idParser :: CharParser () String
idParser = do char '#'
              many1 termChar

classParser :: CharParser () String
classParser = do char '.'
                 many1 termChar

attributesParser :: CharParser () [(String, String)]
attributesParser = squares (commaSep1 attributeParser)

attributeParser :: CharParser () (String, String)
attributeParser = do k <- identifier
                     symbol "="
                     cs <- many1 identifier
                     return (k, intercalate " " cs)

stringParser :: CharParser () String
stringParser = do   currentPos <- getPosition
                    modifier <- optionMaybe (char '=' <|> char '-')
                    c <- alphaNum
                    cs<- tilEOL
                    case modifier of
                      Just '-' -> return $ (indent currentPos) ++ "-" ++ c:cs
                      Just '=' -> return $ (indent currentPos) ++ "(stringToHtml " ++ c:cs ++ ")"
                      Nothing  -> return $ (indent currentPos) ++ "(stringToHtml \"" ++ c:cs ++ "\")"

-- * Utility functions

isInline     p = do p2 <- getPosition
                    case (sourceLine p  ) == (sourceLine p2) of
                      True -> return []
                      False -> pzero
isSameIndent p1 p2 = (sourceColumn p1) == (sourceColumn p2)

tilEOL = manyTill1 (noneOf "\n") eol
eol = newline <|> (eof >> return '\n')

termChar = satisfy (\c -> (isAlphaNum c) || (c `elem` termPunctuation) )
termPunctuation = "-_"
indent p = take (sourceColumn (p) - 1) (repeat ' ')

manyTill1 p e =  do ms <- manyTill p e
                    case (null ms) of
                      True  -> pzero
                      False -> return ms

Golly, but I wish that I’d cleaned up the code, but there it is in all of its raw, un-thought-through glory…

Written by alson

December 11th, 2008 at 1:56 am

Posted in Geekery,Programming

Tagged with , ,

ANNOUNCE: Turbinado V0.2 “Still Ugly”

without comments

More progress on Turbinado. Look! A whole “+0.1”!

Progress continues on Turbinado.  Turbinado can be found at:

The source can be found at:
   (see the /App directory for the code for

New in V0.2:
  * A better "Environment" type (rather than using Dynamics) (-> a 50%
speed boost?  That's unpossible!);
  * A functional early version of an ORM for PostgreSQL (note: still
needs to handle updates; hdbc-postgresql has a bug with sensing
nullable columns);
  * A prettier website;
  * Licensing -> BSD.

Expect V0.3 in the next week or so with:
  * More view helpers;
  * An ORM which handles INSERT/UPDATE...;
  * A little CMS built using the ORM.

Future release:
  * Separate the website out from the framework.  For now, they're
evolving together, so live together. 

Written by alson

November 26th, 2008 at 2:11 am

ANNOUNCE: Turbinado V0.1

without comments

Posted to the Haskell mailing list:

I'd like to announce Turbinado, a very young and raw MVC web framework
for Haskell.  While the framework doesn't exactly copy Ruby on Rails,
it certainly rhymes...  It's very early days for Turbinado, but the
framework is moving along nicely.  There are still issues to be ironed
out and architectural details to be decided, so help/contribution would be
very much appreciated.

Turbinado can be found at:
<a rel="nofollow" href="" target="_top"></a>

The source can be found at:
<a rel="nofollow" href="" target="_top"></a>
(see the /App directory for the code for

* Provides a fast web server (based on HSP; see
<a rel="nofollow" href=";" target="_top">;</a>
* Provides a straightforward organization for your website (courtesy
of Rails);
* Uses simple HTML-like templating (courtesy of HSX);
* Is easily extensible (courtesy of an Environment built out of _Map
String Dynamic_, not the most type-safe of beasties; Help!);
* Configurable routing (see Config/Routes.hs).

Turbinado is currently lacking:
* Documentation...
* An easy install...
* A database ORM based on HDBC (visibly incomplete and ugly in
* Many more HTML helpers;
* Controllers for partials (lightweight "controls" ala ASP.NET);
* Strong error reporting and handling;
* Lots of functionality and plugins;
* ... the favorite feature that you want to develop for Turbinado ...

Written by alson

November 18th, 2008 at 2:10 am

6 Sigma vs. 4 Sigma (or Should The Web Be Sloppy?)

without comments

You’ve probably heard of Six Sigma, the quality management philosophy/practice started at Motorola. Great way to identify problem areas of product design, development and production. Sets a goal of having 99.9997% efficiency in the product life cycle.

We have a fairly traditional SDLC process for our web site development and I’ve been thinking about what the “right” process is for our development efforts. While poking around, I’ve seen a few blog posts about applying six sigma to web marketing or software development.

Got me thinking: should 6 sigma be applied to web software development? Maybe 4 sigma would be better?

Really, do I want NetFlix to provide me with 99.9997% quality in their website? Well, they better handle credit cards with 99.9997% accuracy, but I would prefer that they provide very good quality on their website and focus on rolling out new and improved features. I wouldn’t be too irked if their recommendation engine got better and, in return, I saw an occasional visual flaw or 404. Considering that most web flaws are quickly spotted and easily fixed, it makes some sense to “release early, release often”: don’t overinvest in quality when fixing the issue costs little in terms of time, money or reputation, especially when the benefit of additional features to the user is great.

What about Microsoft Windows? Unlike a web application, I have to install this bit of software and, unlike a web application, it’s not easily updated.

So I’ll vote for Four Sigma quality levels on non-critical areas of consumer websites. 99.379% quality in features is pretty good and I won’t lose sleep over the 0.621% of features that have some issues… But we’ll commit to fix them ASAP.

Written by alson

September 1st, 2008 at 2:11 pm

Posted in Management,Programming

Tagged with ,