9ef28bb53a
- Lexer: added 'type' and 'where' keywords
- AST: TypeExpr::Refined, Declaration::TypeAlias, LetDecl.type_annotation
- Parser: parse_type_alias_decl, parse_type_expr (Named, Generic, where)
- Type system: Type::Refined, Predicate/PredicateExpr with evaluate_static()
- Errors: RefinementViolation, TypeAliasCycle (Elm-style messages)
- Checker: type alias registry, resolve_type_expr, ast_to_predicate,
static refinement checking for literal values
- Codegen: Phase 1b runtime guards, predicate_to_js helper
Syntax: type PositiveInt = Int where value > 0
let count: PositiveInt = 5 -- static check passes
let count: PositiveInt = -1 -- compile error
118 tests pass (16 in ds-types, 5 new for refinements)
27 lines
715 B
Text
27 lines
715 B
Text
-- DreamStack Dependent Types Example
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-- Demonstrates refinement types, type aliases, and type annotations
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-- Type aliases with refinement predicates
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type PositiveInt = Int where value > 0
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type Percentage = Float where value >= 0.0
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-- Basic type annotations
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let count: Int = 0
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let name: String = "hello"
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-- Annotated with refinement type alias
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let priority: PositiveInt = 1
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let progress: Percentage = 75.0
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-- Derived values don't need annotation (inferred)
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let doubled = count * 2
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let greeting = "Welcome, {name}!"
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view main = column [
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text "Count: {count}"
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text "Priority: {priority}"
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text "Progress: {progress}%"
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text greeting
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button "+" { click: count += 1 }
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button "-" { click: count -= 1 }
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]
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