Geir O. Jerstad
646c8bbc20
- Split complex nested functions into focused, single-responsibility helpers - Created io/ directory with pure command builders and impure executors - Eliminated parentheses complexity that was causing compilation errors - SSH module now compiles and runs successfully with cleaner architecture 🤖 Generated with [Claude Code](https://claude.ai/code) Co-Authored-By: Claude <noreply@anthropic.com>
95 lines
No EOL
2.9 KiB
Markdown
95 lines
No EOL
2.9 KiB
Markdown
# Lab Tool Refactoring Plan - Functional Programming Approach
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## Current Problems
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- Deep nested parentheses causing syntax errors
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- Functions doing too many things
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- Hard to debug and maintain
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- Mixed pure/impure logic
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## New Structure
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```
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lab-tool/
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├── core/
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│ ├── config.scm # Pure config access
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│ ├── machine.scm # Pure machine data structures
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│ └── commands.scm # Pure command building
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├── io/
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│ ├── ssh.scm # Pure SSH command building
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│ ├── rsync.scm # Pure rsync command building
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│ └── shell.scm # Impure shell execution
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├── deploy/
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│ ├── ssh-strategy.scm # Pure deployment strategy
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│ ├── deploy-rs-strategy.scm # Pure deploy-rs strategy
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│ └── executor.scm # Impure deployment execution
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├── health/
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│ ├── checks.scm # Pure health check logic
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│ └── monitor.scm # Impure health monitoring
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└── main/
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├── cli.scm # Pure CLI parsing
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├── dispatcher.scm # Pure command dispatch
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└── runner.scm # Impure main execution
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```
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## Functional Principles
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### 1. Single Responsibility Functions
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```scheme
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;; Instead of one complex function doing everything:
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(define (deploy-complex machine options) ...)
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;; Break into focused functions:
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(define (build-rsync-command source dest ssh-config) ...)
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(define (build-nixos-rebuild-command flake-path machine mode) ...)
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(define (execute-command command) ...)
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(define (compose-ssh-deployment rsync-cmd rebuild-cmd) ...)
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```
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### 2. Pure vs Impure Separation
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```scheme
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;; Pure: No side effects, testable
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(define (make-ssh-target user hostname)
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(format #f "~a@~a" user hostname))
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;; Impure: Clear side effects
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(define (execute-ssh-command ssh-config command)
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(system (build-ssh-command ssh-config command)))
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```
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### 3. Function Composition
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```scheme
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;; Instead of deep nesting:
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(let ((config (get-ssh-config machine))
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(command (build-command ...))
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(result (execute (format ...))))
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(if (success? result) ...))
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;; Use composition:
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(-> machine
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get-ssh-config
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(build-deployment-commands flake-path)
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execute-deployment
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handle-result)
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```
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### 4. Error Handling as Values
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```scheme
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;; Instead of exceptions in nested calls:
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(catch #t (lambda () (complex-nested-operation)) error-handler)
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;; Return result types:
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(define (safe-ssh-connect machine)
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(if (valid-config? machine)
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`(success . ,(make-connection machine))
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`(error . "Invalid SSH config")))
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```
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## Implementation Steps
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1. **Extract SSH utilities** (no more parentheses hell)
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2. **Create pure command builders**
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3. **Separate execution layer**
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4. **Build composable deployment strategies**
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5. **Clean CLI interface**
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This will make debugging much easier - each small function can be tested independently! |