Brandon Lucas
0b5abece5f
Standard examples (examples/standard/): - hello_world: Basic effect usage - fizzbuzz: Classic programming exercise - factorial: Recursive and tail-recursive versions - primes: Prime number generation - guessing_game: Interactive Random + Console effects - stdlib_demo: Demonstrates List, String, Option, Math modules Showcase examples (examples/showcase/): - ask_pattern: Resumable effects for config/environment - custom_logging: Custom effect with handler - early_return: Fail effect for clean error handling - effect_composition: Combining multiple effects - higher_order: Closures and function composition - pattern_matching: ADTs and exhaustive matching Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
40 lines
1.1 KiB
Plaintext
40 lines
1.1 KiB
Plaintext
// The "Ask" Pattern - Resumable Effects
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//
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// Unlike exceptions which unwind the stack, effect handlers can
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// RESUME with a value. This enables "ask the environment" patterns.
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//
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// Expected output:
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// Need config: api_url
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// Got: https://api.example.com
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// Need config: timeout
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// Got: 30
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// Configured with url=https://api.example.com, timeout=30
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effect Config {
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fn get(key: String): String
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}
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fn configure(): String with {Config, Console} = {
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Console.print("Need config: api_url")
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let url = Config.get("api_url")
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Console.print("Got: " + url)
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Console.print("Need config: timeout")
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let timeout = Config.get("timeout")
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Console.print("Got: " + timeout)
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"Configured with url=" + url + ", timeout=" + timeout
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}
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handler envConfig: Config {
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fn get(key) =
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if key == "api_url" then resume("https://api.example.com")
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else if key == "timeout" then resume("30")
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else resume("unknown")
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}
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fn main(): Unit with {Console} = {
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let result = run configure() with { Config = envConfig }
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Console.print(result)
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}
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let output = run main() with {}
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