α1 compliance checklist

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Core Language

• No exceptions or implicit panics
• const by default; var only when necessary
• Explicit inout for by-reference mutation
• Boolean conditions are explicit (== true, != false)
• Explicit number casts (u32(x), not implicit)
• No optional chaining; handle T? via match or explicit checks
• Single equality operator == (no ===)
• No implicit type coercion

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Type System

• Strict nominal typing (no accidental structural compatibility)
• No any type; use unknown with explicit narrowing
• Explicit variance annotations (in/out) where needed
• Conditional types non-distributive by default
• Literal type preservation with const

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Functions

• function keyword for all functions (named, anonymous, inline)
• No arrow syntax (=>)
• No fn shorthand
• Function signatures always explicit (params, return, error, effects)

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Effects

• Functions declare effects [...] when performing side effects
• Public/ABI exports explicitly declare effects
• Effect subset rule enforced: called effects ⊆ caller effects
• Async suspension only with appropriate effects (net, io, time)
• Effect polymorphism via spread syntax (...)

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Errors

• Standalone error types declared outside domains
• Domains as unions of error types
• Pick/Omit for precise error subsets
• error E clause on fallible functions
• Public exports explicitly declare error domain
• ok/err only used in functions with error E
• Error values carry context frames
• Propagation uses check/ensure/map_error

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Polymorphism

• No role/trait/protocol keywords
• No impl blocks
• No method syntax (x.method())
• No self keyword
• Operations defined as record types
• Implementations as namespaced constants (Type.impl)
• Explicit parameter passing for polymorphism

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Capabilities

• Capability parameters marked with cap
• Capabilities passed explicitly (no ambient authority)
• fs effect requires Fs capability
• net effect requires Net capability
• time effect requires Clock capability
• rng effect requires Rng capability

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Memory

• Regions explicitly created and disposed
• defer region.dispose() for cleanup
• Views carry region ID
• No reading uninitialized memory
• Mutable views have exclusive access
• Region transfer is explicit (view.move, view.copy)

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Packages

• deps.fe for dependencies (CLI-editable)
• build.fe for complex build logic (optional)
• Content addresses computed by tooling
• ferrule.lock committed for reproducibility
• Package capabilities declared and enforced

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Generics

• Explicit variance (in/out)
• Const generics for type-level values
• Conditional types with infer
• Non-distributive by default
• Variadic generics (...Ts)

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Style

• Types use PascalCase
• Variables/functions use camelCase
• Avoid deep nesting; use early returns
• Comments add value; no filler comments
• Input validation at boundaries
• No hardcoded secrets

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Tooling

• deps.fe is valid
• ferrule.lock is up to date
• All compiler errors resolved
• All warnings addressed or explicitly allowed
• Tests pass in deterministic mode

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Summary Table