1-input.nix

{ f = x: x; a=1; b=2; list = [ a f b ]; }

2-output

{ type: 'set',
  assignments: 
   [ { type: 'assignment',
       identifier: { type: 'identifier', identifier: 'f' },
       expression: 
        { type: 'functionDefinition',
          argument: { type: 'identifier', identifier: 'x' },
          body: { type: 'identifier', identifier: 'x' } } },
     { type: 'assignment',
       identifier: { type: 'identifier', identifier: 'a' },
       expression: { type: 'numberLiteral', value: '1' } },
     { type: 'assignment',
       identifier: { type: 'identifier', identifier: 'b' },
       expression: { type: 'numberLiteral', value: '2' } },
     { type: 'assignment',
       identifier: { type: 'identifier', identifier: 'list' },
       expression: 
        { type: 'list',
          items: 
           [ { type: 'identifier', identifier: 'a' },
             { type: 'identifier', identifier: 'f' },
             { type: 'identifier', identifier: 'b' } ] } } ] }
----
{
f = x: x;
	a = 1;
	b = 2;
	list = [ a f b ];
	}