Functional Parsing - Computerphile

Functional or Combinator Parsing explained by Professor Graham Hutton.


This video was filmed and edited by Sean Riley.

Types 20+ lines of Haskell program in a single breath, then gets 0 warnings or errors from GHC, then goes on as if it is totally normal...

[PaxiKaksi]

So glad my university teaches Haskell. Even if you dont ever use it in your work, learning to program in that language makes you a better programmer and writing a compiler is usually a thing that Haskell will be used for.

[ruskiikoshka]

The videos of this guy are a treasure, thanks a lot!

[olamarvin]

"It doesn't matter if you know any Haskell, because I'll be explaining everything as I go along. So you won't understand a thing either way."

[gist]

say it takes a string as an input and returns a tree as an output one...more...time

[JobvanderZwan]

Regarding the "list of results" remark, maybe a fun example would be a parser that can handle all possible interpretations of "time flies like an arrow, fruit flies like a banana"

[BrankoDimitrijevic]

The key (which IMHO was not so well explained in the video) is that you have a function (parser combinator) that takes other functions (parsers) as input, and produces a function (more complex parser) as a result.


This is rather similar to "normal" recursive-descent parsing, except you don't do the combining yourself, and instead let the parser combinator do it for you.

[maxclifford]

Had to pause the video say, after studying parsers a lot recently I think the beginning explanation is on of the best of what a parser actually is

[StephenFarthing]

Thanks, that was very illuminating. And it’s nice to see Haskell being used in a practical setting.

[elgalas]

Graham Hutton. Your Haskell book was incredibly useful!! Never clicked so fast on a computerphile video. Parsing in Haskell was a bit hard in the beginning though.

[photojournalists]

WOW! Anyone saw the beautiful recursion in the definition of these expression parsers? I don't have the kind of brain to quickly think recursively like this

[st_ProCactus]

This should be a whole series on its own channel... I think a channel dedicated to programming the simple things. Things like this video, but things like... Graphics, calculate a line, circle, plasma, transparncy, sprites, theres heaps and heaps of things like that, 3D rotation vertex and bitmap.. processing raw data by a microphone is another 100 videos. I could go on...
Maybe

[MrMuchoscojones]

Having trouble parsing Grahams accent. Sounds like its from everywhere in the UK at once! Fascinating

[harleyspeedthrust]

I did this with Java, I wrote a postfix expression parser that could do symbolic differentiation and simplification. I used polymorphism to implement the tree structure

[dmitryplatonov]

One thing here is that parser he implemented does binary opetator evaluation right-to left. Left-to-right binary operators are more involving.

[MarkusBurrer]

It is a bit annoying that the camera switches from head to laptop to screen constantly

[AndreasEDM]

What an excellent complement to the material found in his book! Hope to see more

[manantank]

"4 and half screen fulls and is full fledged and can basically implement any parser you like" - mic drop

[SleepyFracture]

Where was this video for my Language Engineering unit at university?! This would've been so useful to refer to!

[luisalejandrohernandezmaya]

Why don't you use Maybe monad instead of List monad?
I think it would be better and more intuitive.
I mean:
type Parser a=String->Maybe (a, String)