45e1d57536
- Decision recorded in CURRENT_TASK: replace with (no compat alias) - EBNF: add match_expr/pattern/guard; note legacy peek removal - Guides/Reference: update examples and wording (null-coalesce/safe-access sugar via match)
59 lines
2.2 KiB
Markdown
59 lines
2.2 KiB
Markdown
# Nyash Language Guide
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Start here to learn Nyash language basics and find deeper references.
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- Syntax Cheat Sheet: quick-reference/syntax-cheatsheet.md
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- Full Language Reference (2025): reference/language/LANGUAGE_REFERENCE_2025.md
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- Phase 12.7 Grammar (match / ternary / sugar):
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- Overview: development/roadmap/phases/phase-12.7/grammar-specs/README.md
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- Tokens & Grammar: development/roadmap/phases/phase-12.7/ancp-specs/ANCP-Token-Specification-v1.md
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- Sugar transformations (?., ??, |> ...): tools/nyfmt/NYFMT_POC_ROADMAP.md
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Common Constructs
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- Ternary operator: `cond ? then : else` (Phase 12.7); lowered to If-expression
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- Match expression (pattern matching): `match value { pat => expr, _, ... }`
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- Null-coalesce: `x ?? y` → `match x { null => y, _ => x }`
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- Safe access: `a?.b` → `match a { null => null, _ => a.b }`
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Minimal Examples
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- Ternary
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```nyash
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static box Main {
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main(args) {
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local a = 3
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local b = 5
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// Nested ternary is supported
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local v = (a < b) ? ((b < 0) ? 40 : 50) : 60
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return v
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}
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}
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```
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- Match as expression block (last expression is the value)
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```nyash
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static box Main {
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main(args) {
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local d = "1"
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// Each arm can be a block; the last expression becomes the value
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local dv = match d {
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"0" => { print("found zero") 0 }
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"1" => { print("found one") 1 }
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_ => { print("other") 0 }
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}
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return dv
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}
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}
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```
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must_use Notes
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- Match arms are expressions. When using a block arm `{ ... }`, the last expression is the resulting value; statements without a final expression yield no usable value.
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- Ternary is an expression; ensure both branches are type-compatible at MIR level (e.g., both yield integer or both yield string handle in current phase).
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When you need the implementation details
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- Tokenizer: src/tokenizer.rs
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- Parser: src/parser/expressions.rs, src/parser/statements.rs
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- Lowering to MIR: src/mir/builder/**
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Statement Separation (Semicolons)
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- Newline separates statements by default; semicolons are optional.
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- Use semicolons only when placing multiple statements on one line.
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- Minimal ASI rules: newline does not end a statement when the line ends with an operator/dot/comma, or while inside grouping.
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