[filter]

filter is a core slot, one of the keywords of the Hyperlambda language, in Hyperlambda, the language of Magic Cloud. Filters selected nodes using the child lambda as a predicate.

• Value (node-list), required: Expression selecting the nodes to filter
• Returns: Resolves to clones of the selected nodes whose predicate body returns true

Arguments

Required arguments come first, then the optional ones in the order they are declared.

Argument	Type	Required	Description
any node name	lambda	yes	Predicate body evaluated once per selected node; the selected node is kept when the body returns true. Can be repeated.

Guide: How to use [filter]

JSON declaration

This is the complete declaration of filter, as the running system describes it. It is also published as slot.json.

JSON declaration

{
  "name": "filter",
  "description": "Filters selected nodes using the child lambda as a predicate",
  "signature": {
    "input": {
      "kind": "node-list",
      "description": "Expression selecting the nodes to filter",
      "required": true,
      "mode": "Expression"
    },
    "children": {
      "*": {
        "type": "lambda",
        "kind": "boolean",
        "description": "Predicate body evaluated once per selected node; the selected node is kept when the body returns true",
        "required": true,
        "mode": "ExecutableLambda",
        "cardinality": "OneOrMore",
        "role": "Condition",
        "evaluation": "EvalSelf",
        "projection": "ReturnedResult"
      }
    },
    "output": {
      "mode": "Lambda",
      "kind": "node-list",
      "description": "Resolves to clones of the selected nodes whose predicate body returns true"
    }
  }
}

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