Constant (Atom Wrapper)

Definition

Constant Atom

Fields

Description

Constant wraps an Atom to make it a valid expression node. All literal values in Nix (integers, booleans, null, URIs) are represented as Constant containing an Atom.

Nix Source ↔ AST

# Nix
42

# AST
{
  "tag": "Constant",
  "contents": { "tag": "Int", "contents": 42 }
}

# Nix
true

# AST
{
  "tag": "Constant",
  "contents": { "tag": "Bool", "contents": true }
}

# Nix
null

# AST
{
  "tag": "Constant",
  "contents": { "tag": "Null" }
}

Related

• Atom: the wrapped atomic types (Int, Float, Bool, Null, Uri)
• See Atoms for atom constructors

Nix Library Access

syntax.mkConstant (syntax.mkInt 42)
syntax.mkConstant (syntax.mkBool true)
syntax.mkConstant syntax.mkNull