code? (schema -- isBlock)

Inputs

• schema: Value or Ref whose dereferenced schema is tested for Block.

Outputs

• isBlock: Known Cond result that is TRUE when schema dereferences to Block.

code? is a dereferenced-schema predicate. It tests whether the dereferenced schema is Block.

The name is historical: code? is the Block test, while codeRef? is the Code test.

Ref inputs are followed before the test. Current value contents do not participate, and the result does not report general callability.

code? is not a general callability test. Use codeRef? for Code schemas and call to attempt an actual call.

Behavior

• The result is always known.
• The result depends only on the dereferenced schema of schema.
• TRUE means the schema is Block.
• All non-Block schemas, including Code and Text, report FALSE.
• Known and unknown values of the same schema always produce the same result.

Example

"String" use

{} 0 {} [
  codeLocal: {} () {} codeRef;
  textLocal: 0 ("") dynamic @;
  [("-- code call --\n") printList] !codeLocal

  "-- code? versus codeRef? --" printCompilerMessage
  [("-- block call --\n") printList] code? printStack _:;
  [("-- block call --\n") printList] codeRef? printStack _:;
  @codeLocal code? printStack _:;
  @codeLocal codeRef? printStack _:;

  "-- not a general callability test --" printCompilerMessage
  «1 +» code? printStack _:;
  textLocal code? printStack _:;

  [("-- block call --\n") printList] call
  @codeLocal call
  0
] "main" exportFunction

Module-loading wrapper lines are omitted below.

Expected Output During Compilation

-- code? versus codeRef? --
TRUE
FALSE
FALSE
TRUE
-- not a general callability test --
FALSE
FALSE

Expected Output

-- block call --
-- code call --

See also

• alignment builtin (schema -- alignment) Returns the storage alignment requirement of the dereferenced schema.
• call builtin (callable -- calledResult) Calls an already-selected callable instead of testing its schema.
• codeRef? builtin (schema -- isCode) Code dereferenced-schema test.
• isCombined builtin (schema -- isCombined) Struct-group dereferenced-schema test.
• managed? builtin (schema -- isManaged) Managed-lifetime dereferenced-schema test.
• same builtin (leftSchema rightSchema -- isSameSchema) Exact dereferenced-schema equality test.
• schemaName builtin (schema -- reportedName) Reported name of the dereferenced schema.
• storageSize builtin (schema -- size) Returns the storage size of the dereferenced schema.
• virtual? builtin (schema -- isMeta) Historical Meta dereferenced-schema test.