Struct LambdaFn 

pub struct LambdaFn;

Trait Implementations

impl Debug for LambdaFn

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Function for LambdaFn

Creates an anonymous callable that can be invoked with spreadsheet arguments.

LAMBDA captures its defining local scope and returns a reusable function value.

Remarks

• All arguments except the last are parameter names; the last argument is the body expression.
• Parameter names must be unique (case-insensitive), or #VALUE! is returned.
• Invocation arity must exactly match the declared parameter count.
• Returning an uninvoked lambda as a final cell value yields a #CALC! in evaluation.

Examples

title: "Inline lambda invocation"
formula: "=LAMBDA(x,x+1)(41)"
expected: 42

title: "Lambda captures outer LET bindings"
formula: "=LET(k,10,addk,LAMBDA(n,n+k),addk(5))"
expected: 15

title: "Duplicate parameter names are invalid"
formula: "=LAMBDA(x,x,x+1)"
expected: "#VALUE!"

related:
  - LET
  - IF
  - SUM
faq:
  - q: "Why does =LAMBDA(x,x+1) return #CALC! instead of a number?"
    a: "LAMBDA returns a callable value. In a cell result position, it must be invoked, for example =LAMBDA(x,x+1)(1)."
  - q: "Does a LAMBDA read outer LET variables at call time or definition time?"
    a: "Definition time. The closure captures its lexical environment when created."
  - q: "Can I call a LAMBDA with fewer or extra arguments?"
    a: "No. Invocation arity must match the declared parameter count exactly, or #VALUE! is returned."

[formualizer-docgen:schema:start] Name: LAMBDA Type: LambdaFn Min args: 1 Max args: variadic Variadic: true Signature: LAMBDA() Arg schema: <unavailable: arg_schema panicked> Caps: PURE, SHORT_CIRCUIT [formualizer-docgen:schema:end]

fn caps(&self) -> FnCaps

Capability flags for this function

fn name(&self) -> &'static str

fn min_args(&self) -> usize

fn variadic(&self) -> bool

fn dispatch<'a, 'b, 'c>( &self, args: &'c [ArgumentHandle<'a, 'b>], ctx: &dyn FunctionContext<'b>, ) -> Result<CalcValue<'b>, ExcelError>

Dispatch to the unified evaluation path with automatic argument validation.

fn eval<'a, 'b, 'c>( &self, args: &'c [ArgumentHandle<'a, 'b>], _ctx: &dyn FunctionContext<'b>, ) -> Result<CalcValue<'b>, ExcelError>

The unified evaluation path.

fn namespace(&self) -> &'static str

fn volatile(&self) -> bool

fn arg_schema(&self) -> &'static [ArgSchema]

fn aliases(&self) -> &'static [&'static str]

Optional list of additional alias names (case-insensitive) that should resolve to this function. Default: empty slice. Implementors can override to expose legacy names. Returned slice must have ’static lifetime (typically a static array reference).

fn function_salt(&self) -> u64

fn eval_reference<'a, 'b, 'c>( &self, _args: &'c [ArgumentHandle<'a, 'b>], _ctx: &dyn FunctionContext<'b>, ) -> Option<Result<ReferenceType, ExcelError>>

Optional reference result path. Only called by the interpreter/engine when the callsite expects a reference (e.g., range combinators, by-ref argument positions, or spill sources).