roc/test/snapshots/match_expr/list_rest_scoping.md

META

description=Match expression with list rest patterns testing variable scoping
type=expr

SOURCE

match items {
    [first, ..rest] => first + 1
    [..rest, last] => last + 2
    [x, ..rest, y] => x + y
}

EXPECTED

BAD LIST REST PATTERN SYNTAX - list_rest_scoping.md:2:13:2:19 BAD LIST REST PATTERN SYNTAX - list_rest_scoping.md:3:6:3:12 BAD LIST REST PATTERN SYNTAX - list_rest_scoping.md:4:9:4:15 UNDEFINED VARIABLE - list_rest_scoping.md:1:7:1:12 UNUSED VARIABLE - list_rest_scoping.md:2:15:2:15 UNUSED VARIABLE - list_rest_scoping.md:3:8:3:8 UNUSED VARIABLE - list_rest_scoping.md:4:11:4:11

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_rest_scoping.md:2:13:2:19:

    [first, ..rest] => first + 1

        ^^^^^^

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_rest_scoping.md:3:6:3:12:

    [..rest, last] => last + 2

 ^^^^^^

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_rest_scoping.md:4:9:4:15:

    [x, ..rest, y] => x + y

    ^^^^^^

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

list_rest_scoping.md:1:7:1:12:

match items {

  ^^^^^

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_rest_scoping.md:2:15:2:15:

    [first, ..rest] => first + 1

          ^

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_rest_scoping.md:3:8:3:8:

    [..rest, last] => last + 2

   ^

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_rest_scoping.md:4:11:4:11:

    [x, ..rest, y] => x + y

      ^

TOKENS

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

PARSE

(e-match
	(e-ident (raw "items"))
	(branches
		(branch
			(p-list
				(p-ident (raw "first"))
				(p-list-rest (name "rest")))
			(e-binop (op "+")
				(e-ident (raw "first"))
				(e-int (raw "1"))))
		(branch
			(p-list
				(p-list-rest (name "rest"))
				(p-ident (raw "last")))
			(e-binop (op "+")
				(e-ident (raw "last"))
				(e-int (raw "2"))))
		(branch
			(p-list
				(p-ident (raw "x"))
				(p-list-rest (name "rest"))
				(p-ident (raw "y")))
			(e-binop (op "+")
				(e-ident (raw "x"))
				(e-ident (raw "y"))))))

FORMATTED

match items {
	[first, .. as rest] => first + 1
	[.. as rest, last] => last + 2
	[x, .. as rest, y] => x + y
}

CANONICALIZE

(e-match
	(match
		(cond
			(e-runtime-error (tag "ident_not_in_scope")))
		(branches
			(branch
				(patterns
					(pattern (degenerate false)
						(p-list
							(patterns
								(p-assign (ident "first")))
							(rest-at (index 1)
								(p-assign (ident "rest"))))))
				(value
					(e-binop (op "add")
						(e-lookup-local
							(p-assign (ident "first")))
						(e-num (value "1")))))
			(branch
				(patterns
					(pattern (degenerate false)
						(p-list
							(patterns
								(p-assign (ident "last")))
							(rest-at (index 0)
								(p-assign (ident "rest"))))))
				(value
					(e-binop (op "add")
						(e-lookup-local
							(p-assign (ident "last")))
						(e-num (value "2")))))
			(branch
				(patterns
					(pattern (degenerate false)
						(p-list
							(patterns
								(p-assign (ident "x"))
								(p-assign (ident "y")))
							(rest-at (index 1)
								(p-assign (ident "rest"))))))
				(value
					(e-binop (op "add")
						(e-lookup-local
							(p-assign (ident "x")))
						(e-lookup-local
							(p-assign (ident "y")))))))))

TYPES

(expr (type "a where [a.from_numeral : Numeral -> Try(a, [InvalidNumeral(Str)])]"))