bin/nijs-build/operations.js
function evaluatePackageAsync(filename, attr, format, callback) {
    var pkgs = require(path.resolve(filename)).pkgs;
    
    slasp.sequence([
        function(callback) {
            pkgs[attr](callback);
        },
        
        function(callback, pkg) {
            var expr = nijs.jsToNix(pkg, format);
            callback(null, expr);
        }
    ], callback);
}
function evaluatePackageAsync(filename, attr, format, callback) {
    var pkgs = require(path.resolve(filename)).pkgs;
    
    slasp.sequence([
        function(callback) {
            pkgs[attr](callback);
        },
        
        function(callback, pkg) {
            var expr = nijs.jsToNix(pkg, format);
            callback(null, expr);
        }
    ], callback);
}
function evaluatePackageAsync ( filename , attr , format , callback ) { var pkgs = require ( path . resolve ( filename ) ) . pkgs ; slasp . sequence ( [ function ( callback ) { pkgs [ attr ] ( callback ) ; } , function ( callback , pkg ) { var expr = nijs . jsToNix ( pkg , format ) ; callback ( null , expr ) ; } ] , callback ) ; }
Imports the given package composition CommonJS module and asynchronously
evaluates the specified package.

@param {String} filename Path to the package composition CommonJS module
@param {String} attr Name of the package to evaluate
@param {Boolean} format Indicates whether to nicely format to expression (i.e. generating whitespaces) or not
@param {function(Object, Object)} callback Callback that gets invoked with either an error set if the operation failed, or a string containing the generated Nix expression
Imports the given package composition CommonJS module and asynchronously evaluates the specified package .