The Lambda Calculus, General Term Rewriting and Food Nutrition
Download this episode
Description
Brian Beckman and Erik Meijer are back with another episode of BMO!
In this installment, Brian and Erik spend some time explaining the Lambda Calculus and most of the time digging into a real world application of general term rewriting. The Lambda Calculus is a specialized form of term rewriting (so, it's not really general term rewriting). It's OK... Brian will explain all of this (and more) by way of his general term rewriting system for analyzing the accuracy of Food Nutrition Labels (NFL). If you're curious about term rewriting and its practical application outside of theoretical computer science, then you're in luck. Brian and Erik engage the concepts at play here in their usual fun, engaging, brilliant ways.
Tune in. Enjoy. Learn.
Share
Format
Available formats for this video:
Actual format may change based on video formats available and browser capability.
The Discussion

Always a pleasure to watch! This was supposed to be a monthly one though ...

Wonderful as always!
Aptly, I just wrote an HTML parser using F# "Active Patterns". The parser/serializer is less than 140 lines of code! (I am claiming it to be the world's smallest HMTL parser until proven wrong).
Please see: http://fshtml.codeplex.com/

Interesting that they are using Chrome, shows how open Microsoft actually is.

Delightful!
And I thought that miracle has happened and you may bind lambdas to implicitlytyped variables in C# 5.0 but no...

Erik: "You can parse HTML with regular expressions..."
It turns out you can't: http://stackoverflow.com/questions/1732348/regexmatchopentagsexceptxhtmlselfcontainedtags/1732454#1732454
How about will Roslyn expose some of C# compiler internal TRs to public?

Isn't that first E an ABS? EDIT: I had to start over ... I see now; the whole thing (\x.E) y is in a box and that's APP ... I thought it was just left hand side ... moving on.... :*)

can't believe it came out to 160. what a doozie

Spectacularly awesome!!!
I love substitution systems. In particular Lindenmayer systems. They are so pure and simple that they should be taught to kids. In fact, watching this overdrive, I was thinking how fortunate kids would be with Beckman and Meijer as teachers. Start with term rewriting and go on from there.
Also the way you completely screw over the absurd labelling practices with term rewriting is just delightful to watch.
Thanks!

is there an old untyped language that was mentioned in this video or a similar one? I remember hearing it but I forgot to write it down, Can you help me remember it?

@tertl3: Do you mean TypeFree Lambda Calculus? Like this? http://community.bartdesmet.net/blogs/bart/archive/2009/08/17/misusingc40dynamictypefreelambdacalculuschurchnumeralsandmore.aspx?

FYI, the way they determine the calories is they literally burn the food in a special food burner chamber and they measure the heat output and subtract out the energy of the gas used to burn it.

Hi Brian and Erik,
Thank you for sharing this new experience.
After this time the "general term rewriting" appears (in a universal manner) be a way to rediscover all the sciences.
Every science as"computer science, mathematics, physics" and also cooking (probably the mother of all sciences) is a new art of digesting raw stuffs.
To live is to transform ! 
I developed term rewriting system for automated development of mathematicallybased scientific research: http://andrzej.pownuk.com/selfnethpc/

Very interesting ... but I'm still trying to work it out and despite watching (at least parts) multiple times ... I have so many questions that I'm not sure where to begin. I'd like to play with the code. Any chance of putting that up Brian?
It was great to see Erik grab his head at the thought of having to read some Knuth! But I felt that way about the Bananas paper!

@Richard  here you go feedback always welcome!

did Erik cut a huge fart about 10 min into the video?
I couldnt see what was written on the whiteboards much of the time, you have to have the camera guy zoom in to that 
5 days ago, brianbec wrote
@Richard  here you go feedback always welcome!
Ah thanks Brian! I'll check it out!
Comments closed
Comments have been closed since this content was published more than 30 days ago, but if you'd like to continue the conversation, please create a new thread in our Forums, or Contact Us and let us know.