Add string interpolation (\(expr) syntax)#257
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Implements #230. Adds Swift-style \(expr) interpolation inside double-quoted strings with auto-conversion for Int, Nat, Bool, Byte, and Float64. InterpolatedString is a first-class AST node (canonical form) touching every compiler stage: transformer, type checker, formatter, and WASM codegen. - New AST node InterpolatedString with parts tuple - Transformer: _split_interpolation + _parse_interp_expr helpers - Type checker: auto-to_string dispatch with E148 for unsupported types - Formatter: round-trip preserving \(expr) syntax - WASM codegen: desugars to string_concat/to_string chains - 18 new tests (9 checker + 9 codegen end-to-end) - New conformance test ch04_string_interpolation (44 programs) - Spec sections 1.4 and 4.13.1 documenting the feature Co-Authored-By: Claude <noreply@anthropic.invalid> EOF )
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Summary
Closes #230. Adds Swift-style
\(expr)string interpolation — the fourth and final item in the string builtins roadmap (#198 → #210 → #213 → #230)."hello \(@String.0)","x = \(@Int.0)","a=\(@Int.1), b=\(@Int.0)"*_to_stringbuilt-inInterpolatedStringis a first-class AST node that survives formatting (no desugaring tostring_concatchains at source level)\(...)cannot contain string literals (regex lexer limitation; useletbindings)Files changed (21 files, +682/-40)
Compiler core (9 files):
vera/ast.py—InterpolatedStringdataclass +format_exprupdatevera/transform.py—_split_interpolation,_parse_interp_expr,STRING_LIT/string_lithandlersvera/checker/expressions.py— type synthesis with_TO_STRING_TYPESauto-conversion mapvera/errors.py— E148 error codevera/formatter.py— round-trip\(expr)renderingvera/wasm/inference.py—InterpolatedString→i32_pairin 3 dispatchersvera/wasm/context.py— expression dispatcher +_is_pair_exprvera/wasm/operators.py—_translate_interpolated_string(desugars to synthetic FnCall nodes)vera/codegen/modules.py— guard rail recurse into interpolation partsTests (18 new tests):
ch04_string_interpolation(conformance suite: 43→44 programs)Documentation:
Test plan
mypy vera/— clean (41 source files)pytest tests/ -v— 1,899 tests collected, 1,893 passed, 6 skipped, 0 failedpython scripts/check_conformance.py— all 44 conformance programs passpython scripts/check_examples.py— all 18 examples passpython scripts/check_spec_examples.py— all spec code blocks passpython scripts/check_skill_examples.py— all SKILL.md code blocks passpython scripts/check_version_sync.py— version 0.0.76 consistent🤖 Generated with Claude Code