Type Safe "Everything"

1. Type Safe “EVERYTHING” @andoshin11
 4. 3. 2020
 #tsc_api_study

2. Who am I ? Shin Ando (a.k.a Andy) @andoshin11 - Freelance Full-Stack Developer - TypeScript / Vue.js / React / Go / Ruby / Flutter / Terraform / etc… - ❤ Code Generation!
3. • Powerful editor completion • Easy to analyze code base using AST • Type-level programming • Overall durability • Maintainable • Scalable • F**king AWESOME!! We all love TypeScript, eh? ❤
4. However...
5. Not everyone speaks TypeScript (just yet...)
6. Not everyone speaks TypeScript (just yet...) • Other programming languages (Go, Ruby, Python, Java, etc...) • Query based languages (a.k.a Database) • Statically defined specs (YAML, CSV, Markdown, Excel) • etc...
7. Not everyone speaks TypeScript (just yet...) • Other programming languages (Go, Ruby, Python, Java, etc...) • Query based languages (a.k.a Database) • Statically defined specs (YAML, CSV, Markdown, Excel) • etc...
8. Solution (we need)
9. Basic aproach Parser Transformer TS Compiler 1. Parse input and tokenize into JSON 2. Transform tokens to TypeScript AST 3. Validate AST and emit useful code Outcome
11. Working Projects
12. ① Typing Database Schema (db-recon) • db-recon ( https://github.com/andoshin11/db-recon ) • Generates type-safe db client for Node.js application • Supports MySQL and MSSQL currently
13. ① Typing Database Schema (db-recon)
14. ① Typing Database Schema (db-recon)
15. ① Typing Database Schema (db-recon)
16. ① Typing Database Schema (db-recon) TODO: • Create SQL-to-AST parser • Get semantic diagnostics for raw SQL literal string ( ts-sql-plugin requires DSL ) • Rewrite ejs templates with TS Compiler API
17. ② Typing API Request/Response (squelette) • squelette ( https://github.com/andoshin11/squelette ) • Generates type definitions for API request/response from Open API spec • Toolchain to build your own type-safe API client
18. ② Typing API Request/Response (squelette)
19. ② Typing API Request/Response (squelette)
20. ② Typing API Request/Response (squelette)
21. ② Typing API Request/Response (squelette)
22. ② Typing API Request/Response (squelette) TODO: • Rewrite remaining ejs templates with TS Compiler API • Improve parser and AST format
23. Latest addition
24. Improving DX for express.js
25. Remaining Pains...
26. Remaining Pains... need manual mapping need to define types may contain typo
27. Leads to fatal error in future...
28. What if...
29. All handlers are typed like a magic ‍♂
31. Introducing...
32. typed-oax
33. Generate express.d.ts from Open API
34. Generate express.d.ts from Open API
35. Generate express.d.ts from Open API
36. DEMO
37. typed-oax TODO: • Separate handler types by HTTP Method • Wrap with TS Plugin?