Friday, 13 March 2015
Thursday, 12 March 2015
Wednesday, 11 March 2015
Sync rails public folder aws s3 bucket rake task
https://ariejan.net/2011/01/01/rake-task-to-sync-your-assets-to-amazon-s3cloudfront/
Monday, 2 March 2015
CSE341: Programming Languages, Winter 2013
http://courses.cs.washington.edu/courses/cse341/13wi/
CSE341: Programming Languages, Winter 2013
Course Information
Course Materials
Material in the future naturally subject to change in terms of coverage or schedule
- Unit 1: ML Functions, Tuples, Lists, and More Reading Notes Videos
- L1. Jan 7-9: Course Mechanics, ML Variable Bindings slides: pptx pdf pdf6up code: sml
- L2. Jan 9: Functions, Pairs, Lists slides: pptx pdf pdf6up code: sml
- S1. Jan 10: Emacs, SML Mode, Shadowing, Error Messages slides: pdf pdf4up code: errors.sml solutions.sml
- L3. Jan 11: Local Bindings, Options, Benefits of No Mutation slides: pptx pdf pdf6up code: sml
- Unit 2: Datatypes, Pattern Matching, Tail Recursion, and More Reading Notes Videos
- L4. Jan 14: Records, Datatypes, Case Expressions slides: pptx pdf pdf6up code: sml
- L5. Jan 16: More Datatypes and Pattern Matching slides: pptx pdf pdf6up code: sml
- S2. Jan 17: Type Synonyms, Polymorphism, & More slides: pptx pdf code: synonyms.sml generics.sml equality.sml fun_patterns.sml
- L6. Jan 18: Nested Pattern-Matching, Exceptions, Tail Recursion slides: pptx pdf pdf6up code: sml
Tail recursion moved to Jan 23 after the Jan 21 holiday - Unit 3: First-Class Functions and Closures Reading Notes Videos
- L7. Jan 23: First-Class Functions slides: pptx pdf pdf6up code: sml
- S3. Jan 24: Standard-Library Docs, Unnecessary Function Wrapping, Map, & More slides: pdf pdf4up code:sec3.sml higher-order.sml
- L8. Jan 25: Lexical Scope and Function Closures slides: pptx pdf pdf6up code: sml
- L9. Jan 28: Function-Closure Idioms slides: pptx pdf pdf6up code: sml
- Unit 4: ML Modules, Type Inference, Equivalence, & More Reading Notes Videos
- L10. Jan 30: ML Modules slides: pptx pdf pdf6up code: sml
- S4. Jan 31: Mutual Recursion, More Currying, More Modules slides: pptx pdf code: all_pairs.sml bank.sml mutual_rec.sml
- L11. Feb 1: Type Inference slides: pptx pdf pdf6up code: sml
- L12. Feb 4: Equivalence slides: pptx pdf pdf6up
- Course-Motivation Interlude, Feb 4-6 slides pdf pdf6up Videos
- Unit 5: Racket, Delaying Evaluation, Memoization, Macros Reading Notes Videos
- L13. Feb 6-11: Racket Introduction slides: pptx pdf pdf6up code: rkt
- S5. Feb 7 <Midterm Review for Midterm on Feb 8>
- L14. Feb 13: Thunks, Laziness, Streams, Memoization slides: pptx pdf pdf6up code: rkt
Some of the material in L14 is covered in S6 instead - S6. Feb 14: More streams, memoization, etc. slides: pdf pdf6up code: sec6.rkt streams.rkt
- L15. Feb 15: Macros slides: pptx pdf pdf6up code: rkt
- Unit 6: Structs, Implementing Languages, Static vs. Dynamic Typing Reading Notes Videos
- L16. Feb 15-20: Datatype-Style Programming With Lists or Structs slides: pptx pdf pdf6up code: rkt sml
- L17. Feb 20-22: Implementing Languages Including Closures slides: pptx pdf pdf6up code: rkt
Some of the material in L17 is covered in S7 instead - S7. Legal ASTs, Macros as Functions, and More slides: pdf
- L18. Feb 22-25: Static vs. Dynamic Typing slides: pptx pdf pdf6up code: rkt sml
- Unit 7: Ruby, Object-Oriented Programming, Subclassing Reading Notes Videos
- L19. Feb 27: Introduction to Ruby and OOP slides: pptx pdf pdf6up code: lec19_silly.rb lec19_example.rb
- S8. Ruby arrays, hashes, ranges, blocks, and more slides (See also material posted with L20.)
Some of the material in L20 is covered in S8 instead - L20. Mar 1-4: Arrays & Such, Blocks & Procs, Inheritance & Overriding slides: pptx pdf pdf6up code: rb
- L21. Mar 4-6: Dynamic Dispatch Precisely, and Manually in Racket slides: pptx pdf pdf6up code: rb sml rkt
- Unit 8: Program Decomposition, Mixins, Subtyping, and More Reading Notes Videos
- L22. Mar 6-8: OOP vs. Functional Decomposition; Adding Operators & Variants; Double-Dispatch
slides: pptx pdf pdf6up code stage A: sml rb java code stage B: sml rb java code stage C: sml rb java - S9. Mar 7: Double-Dispatch, Expression Problem, Mixins, and Visitors slides: pdf pdf6up code: janken.rb janken.sml helpers.sml mixins.rb visitor.rb visitor.sml
- L23. Mar 8: Multiple Inheritance, Mixins, Interfaces, Abstract Methods slides: pptx pdf pdf6up code: rb
- L24. Mar 11-13: Subtyping slides: pptx pdf pdf6up
- L25. Mar 13: Subtyping for OOP; Comparing/Combining Generics and Subtyping slides: pptx pdf pdf6up
- S10. Mar 14: Review, Especially Subtyping slides: pdf counter-examples
- L26. Mar 15: Course Victory Lap slides: pptx pdf pdf6up
Cross Origin Resource Sharing (CORS) Blocked for Cloudfront in Rails
Using a CDN like AWS Cloudfront helps speed up delivery of static assets to your visitors and reduce the load on your servers. Setting up Cloudfront for your Rails apps is very simple, thanks to gems like asset_sync that work nicely with Rails’ asset pipeline compilation process and S3.
One issue can however be tricky to solve sometimes: CORS blocks.
What is happening?
If your assets are served by a CDN like Cloudfront, they can be served from a domain like
sdf73n7ssa.cloudfront.net while your app is served on www.myawesomeapp.com. This triggers CORS blocking in browsers to stop malicious websites fetching nasty resources while browsing a seemingly nice website.
The most common type of this issue is with fonts when you get something like this:
Font from origin 'https://sdf73n7ssa.cloudfront.net' has been blocked from loading by Cross-Origin Resource Sharing policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'https://www.myawesomeapp.com' is therefore not allowed access.
How to fix it?
When it comes to AWS Cloudfront, the most commonly suggested method is to allow CORS origins on the Cloudfront side. This method involves writing XML configuration code for AWS and uploading it on the S3 side.
There is a better and easier way!
I personally prefer using my DNS subdomains to solve this problem. If my CDN is behind
cdn.myawesomeapp.com instead of sdf73n7ssa.cloudfront.net then browsers are not going to freakout and block them as cross domain security problems.
To point your subdomain to your AWS Cloudfront domain go to AWS Cloudfront control panel, select your Cloudfront distribution and enter your CDN subdomain into the Alternate Domain Names (CNAMEs) field. Something like
cdn.myawesomeapp.com will do.
Now you can go to your DNS provider (like AWS Route 53) and create a CNAME for
cdn.myawesomeapp.com pointing to sdf73n7ssa.cloudfront.net.
You can test your new CDN domain by making sure assets served from it are coming from Cloudfront.
curl -I http://cdn.myawesomeapp.com/assets/image.png
should return something like this
HTTP/1.1 200 OK
Content-Type: image/png
Content-Length: 10414
Connection: keep-alive
Date: Mon, 22 Sep 2014 10:06:41 GMT
Last-Modified: Sun, 06 Jan 2013 16:37:19 GMT
ETag: "1c4bef3752c306b9c14a05b4a19d7d79"
Accept-Ranges: bytes
Server: AmazonS3
Age: 1599
X-Cache: Hit from cloudfront
Via: 1.1 a3c44e1caa58818cd22903047dc0faf4.cloudfront.net (CloudFront)
X-Amz-Cf-Id: sEbH-vV6deQra_YQa144RxtwhuJaWSrq-tpdiFxWdUbDbR2DnhoIrQ== Sunday, 1 March 2015
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