path: root/doc/manual/nix-lang-ref.xml

<chapter>
  <title>Nix Language Reference</title>

  <sect1>
    <title>Grammar</title>

    <para>
    </para>

    <productionset>
      <title>Expressions</title>
      
      <production id="nix.expr">
        <lhs>Expr</lhs>
        <rhs>
          <nonterminal def="#nix.expr_function" />
        </rhs>
      </production>
      
      <production id="nix.expr_function">
        <lhs>ExprFunction</lhs>
        <rhs>
          '{' <nonterminal def="#nix.formals" /> '}' ':' <nonterminal def="#nix.expr_function" />
          <sbr />|
          <nonterminal def="#nix.expr_assert" />
        </rhs>
      </production>
      
      <production id="nix.expr_assert">
        <lhs>ExprAssert</lhs>
        <rhs>
          'assert' <nonterminal def="#nix.expr" /> ';' <nonterminal def="#nix.expr_assert" />
          <sbr />|
          <nonterminal def="#nix.expr_if" />
        </rhs>
      </production>
      
      <production id="nix.expr_if">
        <lhs>ExprIf</lhs>
        <rhs>
          'if' <nonterminal def="#nix.expr" /> 'then' <nonterminal def="#nix.expr" />
          'else' <nonterminal def="#nix.expr" />
          <sbr />|
          <nonterminal def="#nix.expr_op" />
        </rhs>
      </production>
      
      <production id="nix.expr_op">
        <lhs>ExprOp</lhs>
        <rhs>
          '!' <nonterminal def="#nix.expr_op" />
          <sbr />|
          <nonterminal def="#nix.expr_op" /> '==' <nonterminal def="#nix.expr_op" />
          <sbr />|
          <nonterminal def="#nix.expr_op" /> '!=' <nonterminal def="#nix.expr_op" />
          <sbr />|
          <nonterminal def="#nix.expr_op" /> '&amp;&amp;' <nonterminal def="#nix.expr_op" />
          <sbr />|
          <nonterminal def="#nix.expr_op" /> '||' <nonterminal def="#nix.expr_op" />
          <sbr />|
          <nonterminal def="#nix.expr_op" /> '->' <nonterminal def="#nix.expr_op" />
          <sbr />|
          <nonterminal def="#nix.expr_op" /> '//' <nonterminal def="#nix.expr_op" />
          <sbr />|
          <nonterminal def="#nix.expr_op" /> '~' <nonterminal def="#nix.expr_op" />
          <sbr />|
          <nonterminal def="#nix.expr_op" /> '?' <nonterminal def="#nix.id" />
          <sbr />|
          <nonterminal def="#nix.expr_app" />
        </rhs>
      </production>
      
      <production id="nix.expr_app">
        <lhs>ExprApp</lhs>
        <rhs>
          <nonterminal def="#nix.expr_app" /> '.' <nonterminal def="#nix.expr_select" />
          <sbr />|
          <nonterminal def="#nix.expr_select" />
        </rhs>
      </production>
      
      <production id="nix.expr_select">
        <lhs>ExprSelect</lhs>
        <rhs>
          <nonterminal def="#nix.expr_select" /> <nonterminal def="#nix.id" />
          <sbr />|
          <nonterminal def="#nix.expr_simple" />
        </rhs>
      </production>
      
      <production id="nix.expr_simple">
        <lhs>ExprSimple</lhs>
        <rhs>
          <nonterminal def="#nix.id" /> |
          <nonterminal def="#nix.int" /> |
          <nonterminal def="#nix.str" /> |
          <nonterminal def="#nix.path" /> |
          <nonterminal def="#nix.uri" />
          <sbr />|
          '(' <nonterminal def="#nix.expr" /> ')'
          <sbr />|
          '{' <nonterminal def="#nix.bind" />* '}'
          <sbr />|
          'let' '{' <nonterminal def="#nix.bind" />* '}'
          <sbr />|
          'rec' '{' <nonterminal def="#nix.bind" />* '}'
          <sbr />|
          '[' <nonterminal def="#nix.expr_select" />* ']'
        </rhs>
      </production>

      <production id="nix.bind">
        <lhs>Bind</lhs>
        <rhs>
          <nonterminal def="#nix.id" /> '=' <nonterminal def="#nix.expr" /> ';'
          <sbr />|
          'inherit' ('(' <nonterminal def="#nix.expr" /> ')')? <nonterminal def="#nix.id" />* ';'
        </rhs>
      </production>

      <production id="nix.formals">
        <lhs>Formals</lhs>
        <rhs>
          <nonterminal def="#nix.formal" /> ',' <nonterminal def="#nix.formals" />
          | <nonterminal def="#nix.formal" />
        </rhs>
      </production>
          
      <production id="nix.formal">
        <lhs>Formal</lhs>
        <rhs>
          <nonterminal def="#nix.id" />
          <sbr />|
          <nonterminal def="#nix.id" /> '?' <nonterminal def="#nix.expr" />
        </rhs>
      </production>
          
    </productionset>

    <productionset>
      <title>Terminals</title>

      <production id="nix.id">
        <lhs>Id</lhs>
        <rhs>[a-zA-Z\_][a-zA-Z0-9\_\']*</rhs>
      </production>
    
      <production id="nix.int">
        <lhs>Int</lhs>
        <rhs>[0-9]+</rhs>
      </production>
    
      <production id="nix.str">
        <lhs>Str</lhs>
        <rhs>\"[^\n\"]*\"</rhs>
      </production>

      <production id="nix.path">
        <lhs>Path</lhs>
        <rhs>[a-zA-Z0-9\.\_\-\+]*(\/[a-zA-Z0-9\.\_\-\+]+)+</rhs>
      </production>
    
      <production id="nix.uri">
        <lhs>Uri</lhs>
        <rhs>[a-zA-Z][a-zA-Z0-9\+\-\.]*\:[a-zA-Z0-9\%\/\?\:\@\&amp;\=\+\$\,\-\_\.\!\~\*\']+</rhs>
      </production>

      <production id="nix.ws">
        <lhs>Whitespace</lhs>
        <rhs>
          [ \t\n]+
          <sbr />|
          \#[^\n]*
          <sbr />|
          \/\*(.|\n)*\*\/
        </rhs>
      </production>

    </productionset>
    
  </sect1>
  
</chapter>