Unity.Interpreter (Unity v0.6.0)

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Evaluates ASTs produced by Unity.Parser by building Localize.Unit structs and applying operations via Localize.Unit.Math.

The interpreter maintains an environment map for variable bindings (via let) and a special _ binding for the previous result.

Summary

Types

env()
result()

Functions

eval(ast, environment \\ %{})

Evaluates a parsed AST in the given environment.

Types

env()

@type env() :: %{required(String.t()) => Localize.Unit.t() | number()}

result()

@type result() :: Localize.Unit.t() | number() | {:decomposed, [Localize.Unit.t()]}

Functions

eval(ast, environment \\ %{})

@spec eval(term(), env()) :: {:ok, result(), env()} | {:error, String.t()}

Evaluates a parsed AST in the given environment.

Arguments

  • ast - the AST node from Unity.Parser.

  • environment - a map of variable bindings. Defaults to %{}.

Returns

  • {:ok, result, environment} on success, where result is a Localize.Unit.t() or a number, and environment is the updated variable bindings.

  • {:error, message} on failure.

Examples

iex> {:ok, ast} = Unity.Parser.parse("3 meters to feet")
iex> {:ok, result, _env} = Unity.Interpreter.eval(ast)
iex> result.name
"foot"