Every problem Korrin reports is a diagnostic : a stable error code, a
one-line message, one or more labelled spans of source, and optional notes and a
help line. Diagnostics are produced by four stages — lexer, parser, resolver,
interpreter — and rendered the same way regardless of origin
(ADR 0008 ).
Once a code is assigned a meaning it keeps it forever. Wording may improve; the
code–meaning mapping does not change. New codes are appended. The authoritative
list is the ErrorCode enum in crates/korrin/src/diagnostics.rs; this section
is its prose companion.
Lexer and parser errors are collected — one mistake does not hide the
rest — and reported together. The program does not run.Resolver errors are all reported in one pass. The program does not run.A runtime error stops execution immediately at the offending expression.
Output written before that point has already been produced.
Code Meaning
E0001A character that cannot begin any token (includes a lone !). E0002A string literal with no closing " before the end of the line. E0003A \ escape that Korrin does not define. E0004A malformed number literal (1.2.3, 10abc). E0005A number literal outside the range of its type. E0006A tab character in a line's leading indentation. E0007A dedent to a column that matches no enclosing block. E0008An opening (, [, or { with no matching close.
Code Meaning
E0101A token where the grammar does not allow it (includes a chained comparison). E0102A required token (:, ), in, a name, end of line, …) was missing. E0103An expression was required and none was found. E0104The left side of = is not a name, attribute, or index. E0105(reserved) An indented block with no statements.E0106A for header not of the form for NAME in EXPR:.
Code Meaning
E0201return outside any function.E0202break outside any loop.E0203continue outside any loop.E0204(reserved — self is an ordinary name) E0205super outside any method.E0206super in a class with no parent.E0207Two parameters of one function share a name. E0208A class names itself as its own parent.
Code Meaning
E0301Read of a name with no binding in scope. E0302Call of a value that is not a function or class. E0303A call with the wrong number of arguments. E0304An operator, builtin, or method got a value of the wrong type. E0305Integer or float division/modulo by zero. E0306An integer operation overflowed the 64-bit range. E0307A list or string index outside its bounds (includes list.pop / list.remove_at / list.insert out of range). E0308Indexing a value that does not support it. E0309Access of an attribute a value does not have (an unknown instance field/method, or an unknown method on str / list / map). E0310A map[key] lookup for an absent key. E0311A value that is not hashable used as a map key. E0312(reserved for the future error-handling feature) E0313Function-call nesting exceeded the interpreter's recursion limit.
x = 1 + undefined_name
# error: E0301
fn f(a, a):
return a
# error: E0207
print(10 % 0)
# error: E0305