SOURCE

match numbers {
    [] => acc
    [first, ..rest] => 0 # invalid rest pattern should error
}

EXPECTED

BAD LIST REST PATTERN SYNTAX - list_patterns.md:3:13:3:19 UNDEFINED VARIABLE - list_patterns.md:1:7:1:14 UNDEFINED VARIABLE - list_patterns.md:2:11:2:14 UNUSED VARIABLE - list_patterns.md:3:6:3:11 UNUSED VARIABLE - list_patterns.md:3:15:3:15

PROBLEMS

BAD LIST REST PATTERN SYNTAX List rest patterns should use the .. as name syntax, not ..name. For example, use [first, .. as rest] instead of [first, ..rest].

list_patterns.md:3:13:3:19:

    [first, ..rest] => 0 # invalid rest pattern should error

        ^^^^^^

UNDEFINED VARIABLE Nothing is named numbers in this scope. Is there an import or exposing missing up-top?

list_patterns.md:1:7:1:14:

match numbers {

  ^^^^^^^

UNDEFINED VARIABLE Nothing is named acc in this scope. Is there an import or exposing missing up-top?

list_patterns.md:2:11:2:14:

    [] => acc

^^^

UNUSED VARIABLE Variable first is not used anywhere in your code.

If you don't need this variable, prefix it with an underscore like _first to suppress this warning. The unused variable is declared here: list_patterns.md:3:6:3:11:

    [first, ..rest] => 0 # invalid rest pattern should error

 ^^^^^

UNUSED VARIABLE Variable rest is not used anywhere in your code.

If you don't need this variable, prefix it with an underscore like _rest to suppress this warning. The unused variable is declared here: list_patterns.md:3:15:3:15:

    [first, ..rest] => 0 # invalid rest pattern should error

TOKENS

KwMatch,LowerIdent,OpenCurly,
OpenSquare,CloseSquare,OpFatArrow,LowerIdent,
OpenSquare,LowerIdent,Comma,DoubleDot,LowerIdent,CloseSquare,OpFatArrow,Int,
CloseCurly,
EndOfFile,

PARSE

(e-match
	(e-ident (raw "numbers"))
	(branches
		(branch
			(p-list)
			(e-ident (raw "acc")))
		(branch
			(p-list
				(p-ident (raw "first"))
				(p-list-rest (name "rest")))
			(e-int (raw "0")))))

FORMATTED

match numbers {
	[] => acc
	[first, .. as rest] => 0
}

CANONICALIZE

(e-match
	(match
		(cond
			(e-runtime-error (tag "ident_not_in_scope")))
		(branches
			(branch
				(patterns
					(pattern (degenerate false)
						(p-list
							(patterns))))
				(value
					(e-runtime-error (tag "ident_not_in_scope"))))
			(branch
				(patterns
					(pattern (degenerate false)
						(p-list
							(patterns
								(p-assign (ident "first")))
							(rest-at (index 1)
								(p-assign (ident "rest"))))))
				(value
					(e-num (value "0")))))))

TYPES

(expr (type "Error"))

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