isRef (value -- value isRefLike)

Builtins

Name introduction, declaration modifiers, and module binding: NAME: ...;, codeRef, def, exportFunction, importFunction, importVariable, overload, private, static, use, and virtual.
Struct construction forms: (...), {...}, and array.
Selection forms: source-text selection with NAME and .NAME, read-only source-text selection with @NAME and .@NAME, and ordinal or known-name data-input selection with @, callField, and fieldRead.
Writing forms: source-text selection with !NAME and .!NAME, ordinal selection with ! and fieldWrite, and already-selected destination replacement with set.
Calling and control flow: call, if, loop, ucall, and uif.
Text operations: &, LF, attribute, textSize, and textSplit.
Condition constants, value comparison, and logical operators: <, =, >, DEBUG, FALSE, TRUE, and, is, lshift, or, rshift, xor, and ~.
Arithmetic and numeric transforms: *, +, -, /, ^, cast, ceil, cos, floor, log, log10, mod, neg, sin, and sqrt.
Reference, creation, and value-state operations: const, dynamic, isConst, isDirty, isDynamic, isRef, isStatic, known?, new, newVarOfTheSameType, stable?, unconst, and unknownStable?.
Schema and struct introspection: code?, codeRef?, fieldCount, fieldIndex, fieldIsRef, fieldIsVirtual, fieldName, has, isCombined, managed?, same, schemaName, and virtual?.
Storage and manual lifetime operations: addressToReference, alignment, manuallyDestroyVariable, manuallyInitVariable, storageAddress, and storageSize.
Diagnostics and compile-time failure: failCompilation, getCallTrace, printCompilerMessage, printStack, printStackTrace, and raiseStaticError.

isRef (value -- value isRefLike)

Inputs

value: Current stack value whose Ref-like kind is tested.

Outputs

value: Preserved current stack value.

isRefLike: Known Cond result that is TRUE when the current stack value is Ref-like.

isRef is the current stack-value Ref-like predicate. It preserves the current stack value and reports whether that value is Ref-like.

In this builtin, Ref-like means Ref, Code, or Text. Current knownness, mutability, and NIL status do not change that category, so a known NIL Code value and an unknown Ref value are still Ref-like.

It answers the current stack-value question. The selected-item schema question is answered by fieldIsRef. A non-static In-place field can therefore make fieldIsRef return FALSE while a later read of that field makes isRef return TRUE.

Behavior

The original input remains on the stack below the result Cond.

TRUE means that the current stack value is Ref, Code, or Text.

Current knownness and NIL status do not change the result for Ref, Code, or Text values.

In-place values and Meta values report FALSE.

Changing only In-place value contents, for example with dynamic, does not make that value Ref-like.

NAME on an In-place local produces a Ref-like value, while a plain literal of the same schema does not.

Example

{} 0 {} [ plain: 7; unknownText: 0 ("") dynamic @; dict: { ordinaryField: 8; }; "-- field schema versus read result --" printCompilerMessage dict 0 fieldIsRef printStack _:; 0 @dict @ isRef printStack _:; _:; "-- In-place values --" printCompilerMessage 7 isRef printStack _:; _:; 0 dynamic isRef printStack _:; _:; plain isRef printStack _:; _:; @plain isRef printStack _:; _:; "-- Ref-like also includes Text and Code --" printCompilerMessage "hi" isRef printStack _:; _:; unknownText isRef printStack _:; _:; {} () {} codeRef isRef printStack _:; _:; "-- meta value --" printCompilerMessage () isRef printStack _:; _:; 0 ] "main" exportFunction

Expected Output During Compilation

-- field schema versus read result -- FALSE 8 Ref TRUE -- In-place values -- 7 FALSE 0 FALSE 7 Cref TRUE 7 Ref TRUE -- Ref-like also includes Text and Code -- "hi" TRUE Text TRUE {} () {} codeRef CNIL TRUE -- meta value -- () FALSE