Metastatic.Adapters.Elixir.FromMeta (Metastatic v0.10.4)

View Source

Transform MetaAST (M2) back to Elixir AST (M1).

This module implements the reification function ρ_Elixir that instantiates meta-level representations back into Elixir-specific AST structures.

New 3-Tuple Format

All MetaAST nodes are uniform 3-element tuples:

{type_atom, keyword_meta, children_or_value}

Where:

  • type_atom - Node type (e.g., :literal, :binary_op, :function_def)
  • keyword_meta - Keyword list with metadata (line, subtype, operator, etc.)
  • children_or_value - Value for leaf nodes, list of children for composites

Transformation Strategy

Uses Metastatic.AST.traverse/4 for bottom-up AST transformation:

  1. Post-order traversal: Children are transformed before parents
  2. Metadata extraction: Node attributes extracted from keyword metadata
  3. Original metadata restoration: Uses :original_meta when available

Examples

iex> meta_ast = {:literal, [subtype: :integer], 42}
iex> {:ok, elixir_ast} = FromMeta.transform(meta_ast, %{})
iex> elixir_ast
42

iex> meta_ast = {:binary_op, [category: :arithmetic, operator: :+],
...>   [{:variable, [], "x"}, {:literal, [subtype: :integer], 5}]}
iex> {:ok, elixir_ast} = FromMeta.transform(meta_ast, %{})
iex> elixir_ast
{:+, [], [{:x, [], nil}, 5]}

Summary

Functions

transform(meta_ast, metadata \\ %{})

Transform MetaAST back to Elixir AST.

Functions

transform(meta_ast, metadata \\ %{})

@spec transform(term(), map()) :: {:ok, term()} | {:error, String.t()}

Transform MetaAST back to Elixir AST.

Returns {:ok, elixir_ast} on success or {:error, reason} on failure.

Examples

iex> FromMeta.transform({:literal, [subtype: :integer], 42}, %{})
{:ok, 42}

iex> FromMeta.transform({:variable, [], "x"}, %{context: Elixir})
{:ok, {:x, [], Elixir}}