semantic/weekly/2016-09-09.md

September 9th, 2016

• Hack week was last week and we skipped the weekly.
• We moved the weekly to the end of the week to try to cut down on the “wait, what did happen last week?” thing.
• This ended up being @tclem’s first weekly 👋

What went well?

@joshvera:

Hack week:

• Made a lot of progress on the TypeScript parser.
• May be able to use that as the basis for a more rigorous JavaScript parser as well.

This week:

• Understand RWS & some other diffing algos a lot better than before.

@rewinfrey:

• Pairing w/ @tclem.
• Updating test cases is much more efficient.
• Modelling effects in Free.

@tclem:

• Little fixes.
• Static linking of ICU in dev.
• statsd client.

@robrix:

• semantic-diffd
• Docker
• kubes
• Markdown

What were the challenges?

@joshvera:

• Integrating a pass before RWS. Using constant-time (per-subtree)SES before RWS to match up equal things. There are some ordering problems with the result.
• Ambiguities in the TypeScript grammar. Possibly due to JS actually being context-sensitive. @maxbrunsfeld advises parsing a superset of the language… but which superset?

@rewinfrey:

• Trying to get an effect system in Free. Got it, but tricky.
• Also picked up an issue with template strings which defies debugging.

@tclem:

• My head hurts by the end of the day.

• Being challenged by some of the new concepts, the vernacular &c.
• Hard to know when to jump down the rabbit hole and learn a thing or when to gloss over it.
• Have a queue of things to read.

@robrix:

• Converting between line/column ranges and character ranges.

What did you learn?

@joshvera:

• I became one with the TypeScript grammar.

• Maybe we should find a way to have the grammars write themselves.

• Working on this effects package (formerly called freer) & its Eff type. It uses an open union data structure, which Data.Record is sort of an approximation of. Eff has this detail where it’s list of function types are “type-aligned.” Every item in the list is a function type where they all chain together, a -> b, b -> c, etc. Adding, removing, & replacing effects is constant-time.

@rewinfrey:

• Free, and how to model effects in Free.
• Straight-up category theory stuff. Compositions of natural transformations &c.

@tclem:

• Post about functors, applicatives, and monads shown in pictures.
• How this manages to be a bridge between pure & stateful functions.
• Helped explain the optparse-applicative syntax.

@robrix:

• CMark exists, which is cool.
• Parsing/term ingestion had been producing errors for weirdly-formatted for loops &c. Not only were we hitting this on a regular basis, it was also causing confusing/poor change summaries.

Meta

“What were the challenges?” can be a bit redundant with “what did you learn?” Should we focus this on challenges that we need help with? Gonna give that a try.

Next week: @joshvera, @rewinfrey, & @robrix are off to ICFP. @tclem may or may not hold weekly solo at his discretion.