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Change record syntax, fix a few bugs

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This commit is contained in:
Yura Dupyn 2026-02-06 21:52:32 +01:00
parent 13a66f2d16
commit e389e46852
7 changed files with 212 additions and 114 deletions
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65
src/parser/parser.ts
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@ -1,6 +1,6 @@
import { Expr, ExprBinding, FieldAssignment, FieldPattern, MatchBranch, Pattern, ProductPattern } from '../value';
import { Cursor } from './cursor';
import { ExprScanError, exprStart, ExprStartToken, identifier, isNextTokenExprStart, isNextTokenProductPatternStart, patternStart, PatternStartToken, skipWhitespaceAndComments } from './scanner';
import { ExprScanError, exprStart, ExprStartToken, IdentifierKind, identifierScanner, isNextTokenExprStart, isNextTokenProductPatternStart, patternStart, PatternStartToken, skipWhitespaceAndComments } from './scanner';
import { char, CodePoint, SourceText, Span } from './source_text';
import { Result } from '../result';
@ -25,6 +25,7 @@ export type ParseError =
| { tag: "ExpectedPatternAssignmentSymbol", span: Span } // Expected '=' in pattern assignment
| { tag: "ExpectedPatternBindingSymbol", span: Span } // Expected '.' in pattern binding
| { tag: "ExpectedFunctionCallStart", span: Span } // Expected '(' after function name
| { tag: "ExpectedRecordOpen", span: Span } // Expected '(' after ':'
| { tag: "ExpectedLetBlockOpen", span: Span } // Expected '{' after 'let'
| { tag: "ExpectedLetBlockClose", span: Span } // Expected '}' at end of 'let' expression
| { tag: "ExpectedMatchBlockOpen", span: Span } // Expected '{' after 'match'
@ -35,6 +36,7 @@ export type ParseError =
| { tag: "ExpectedApplySeparator", span: Span } // Expected '!' inside 'apply'
| { tag: "UnexpectedTagPattern", span: Span } // Found #tag where product pattern expected
| { tag: "ExpectedPattern", span: Span } // EOF or invalid start of pattern
| { tag: "ExpectedRecordPatternOpen", span: Span } // Expected '(' at start of record pattern
| { tag: "ExpectedRecordField", span: Span }; // Expected identifier in record pattern
// TODO: Delete?
@ -44,6 +46,7 @@ export type Expectation =
| "ExpectedPatternAssignmentSymbol"
| "ExpectedPatternBindingSymbol"
| "ExpectedFunctionCallStart"
| "ExpectedRecordOpen"
| "ExpectedLetBlockOpen"
| "ExpectedLetBlockClose"
| "ExpectedMatchBlockOpen"
@ -53,6 +56,7 @@ export type Expectation =
| "UnexpectedTagPattern"
| "ExpectedPattern"
| "ExpectedRecordField"
| "ExpectedRecordPatternOpen"
export type Parser<T> = (cursor: Cursor) => T
@ -92,7 +96,7 @@ function delimitedTerminalSequence<A>(cursor: Cursor, delimiter: CodePoint, term
//
// All our use-cases always have a well-defined terminator character:
// tuples: ( a, b, c ) -> `)`
// records: { f0 = e0, f1 = e1 } -> `}`
// records: :( f0 = e0, f1 = e1 ) -> `}`
// function call: f(a, b, c) -> `)`
// let-binding: let { p = e . body } -> `.`
// fn-asbtraction: fn { p0, p1 . body } -> `.`
@ -110,6 +114,7 @@ function delimitedTerminalSequence<A>(cursor: Cursor, delimiter: CodePoint, term
}
while (true) {
const item = p(cursor); // `p` should be responsible for getting rid of whitespace after it has done its work
items.push(item);
@ -154,6 +159,12 @@ function patternStartToken(cursor: Cursor): PatternStartToken {
return token;
}
function identifier(cursor: Cursor, kind: IdentifierKind): { name: string, span: Span } {
const result = identifierScanner(cursor, kind);
skipWhitespaceAndComments(cursor);
return result;
}
// === Expression Parsers ===
function expr(cursor: Cursor): Expr {
@ -185,10 +196,6 @@ function expr(cursor: Cursor): Expr {
// e.g. (a, b, c)
const items = delimitedTerminalSequence(cursor, DELIMITER_COMMA, TERMINATOR_CLOSE_PAREN, expr);
return Expr.tuple(items);
case "record_start":
// e.g. { x = 1, y = 2 }
const fields = delimitedTerminalSequence(cursor, DELIMITER_COMMA, TERMINATOR_CLOSE_BRACE, fieldAssignment);
return Expr.record(fields);
case "function_name":
// e.g. my_func(arg1, arg2)
// parse a `,` delimiter sequence of expr
@ -203,6 +210,17 @@ function expr(cursor: Cursor): Expr {
return Expr.call(token.name, args);
case "keyword":
switch (token.kw) {
case ":":
// e.g. :( x = 1, y = 2 )
// or : ( x = 1, y = 2 )
if (!tryConsume(cursor, char('('))) {
throw {
tag: "ExpectedRecordOpen",
span: cursor.makeSpan(cursor.currentLocation())
} as ParseError;
}
const fields = delimitedTerminalSequence(cursor, DELIMITER_COMMA, TERMINATOR_CLOSE_PAREN, fieldAssignment);
return Expr.record(fields);
case "let":
// let { p0 = e0, p1 = e2 . body }
if (!tryConsume(cursor, char('{'))) {
@ -320,7 +338,7 @@ function productPatternBinding(cursor: Cursor): ExprBinding {
function fieldAssignment(cursor: Cursor): FieldAssignment {
// `f = e`
const { name, span } = identifier(cursor, 'identifier');
const { name, span } = identifier(cursor, 'field_name');
if (!tryConsume(cursor, char('='))) {
throw {
@ -385,27 +403,42 @@ function finishProductPattern(cursor: Cursor, token: PatternStartToken): Product
return ProductPattern.tuple(items);
}
case "record_start": {
// { a = p, b }
const fields = delimitedTerminalSequence(cursor, DELIMITER_COMMA, TERMINATOR_CLOSE_BRACE, recordPatternField);
return ProductPattern.record(fields);
}
case "tag":
throw { tag: "UnexpectedTagPattern", span: token.span } as ParseError;
case "keyword": {
switch (token.kw) {
case ":": {
// :( a = p, b )
// TODO: parse open-paren
if (!tryConsume(cursor, char('{'))) {
throw {
tag: "ExpectedRecordPatternOpen",
span: cursor.makeSpan(cursor.currentLocation())
} as ParseError;
}
const fields = delimitedTerminalSequence(cursor, DELIMITER_COMMA, TERMINATOR_CLOSE_PAREN, recordPatternField);
return ProductPattern.record(fields);
}
default:
// These keywords CANNOT start a pattern.
throw { tag: "ExpectedPattern", span: token.span } as ParseError;
}
}
case "EOF":
throw { tag: "ExpectedPattern", span: token.span } as ParseError;
}
}
function recordPatternField(cursor: Cursor): FieldPattern {
const { name, span } = identifier(cursor, 'identifier'); // Reuse existing identifier scanner
const { name, span } = identifier(cursor, 'field_name');
if (tryConsume(cursor, char('='))) {
const p = productPattern(cursor);
return ProductPattern.fieldPattern(name, p);
} else {
// Punning: { a } -> { a = a }
// Punning: :( a ) -> :( a = a )
return ProductPattern.fieldPattern(name, ProductPattern.any(name));
}
}
@ -422,7 +455,7 @@ export function parse(input: string): Result<Expr, ParseError> {
if (!cursor.eof()) {
return Result.error({
tag: "UnexpectedToken",
expected: "End of File",
expected: "EndOfFile",
span: cursor.makeSpan(cursor.currentLocation())
} as ParseError);
}