Lambda

Start a nested callback body. Connect from a Callback outlet (loop, async, and similar). Optionally set local variables.

Type

lambda.start

Block Module

Folderbasic/module

Channels

Any

Pipe

Value

Scope

Callback, async callback

Lambda (palette name Lambda, type lambda.start) is the start of a callback scope. Connect it to a parent Callback outlet — for example a loop — not to the main Out path.

That outlet is a new scope. Blocks after Lambda run only inside the nested body. Named variables from outside still work. This body’s args.* are the callback values from the handle (item, index, and similar). Lambda puts those same callback args on pipe.value for the next block — pipe.value and args.* are the same object. You cannot wire the body back onto the main path except through the parent’s normal Out.

Variables on Lambda are Set in this body only. They do not change names on the outer workflow. Use Update to change an outer name.

A Return after Lambda returns from this body (this iteration or task), not from the whole workflow. The parent loop or task collects that value. That is not the same as Return on the main path after Start.

Lambda is valid in callback and async callback scope only. The builder rejects it on the main path.

Configure

Setting	Description
Output schema (optional)	Shape this body should return. When set, it must match the parent handle’s return shape exactly (for example a for-of item result)
Variables	Optional named values set in this body’s local scope when the lambda starts. Same as Set, including naming rules.

If you leave output schema empty, the parent handle’s return shape is used.

Handles

Handle	Role
In (target)	Connect from the parent Callback (lambda) outlet
Out (source)	Continues the nested body toward Return

Pipe schema

The next block in the body reads this on the data pipe (pipe.value). That value is the args object this invocation received from the parent handle — the same object as args.*.

Keys are exact names from that handle (for example item and index on For Of — not Item). After a later block runs, pipe.value becomes that block’s output; args.* stay the callback args for the rest of the body.

Use case

After a For Of Callback, start the per-item body with Lambda, then Return a mapped value.
Same pattern for For, While, and other callback outlets (including async tasks).
Keep loop logic in its own scope so a Return, Continue, or Break cannot be mistaken for the workflow’s main Return.