Change nucleus.compile to use global scope (closes #27)

api/nucleus.md

@@ -61,13 +61,9 @@ A string describing the JS engine. It can contain values like `"duktape"`,
 
 ### nucleus.compile(string, path) -> function
 
-Compiles the `string` into a JavaScript function with a file context of `path`,
-used in generating error stacktraces.
-
-The source is wrapped in `function () { ... }` and run in function mode.
-
-TODO: should add access to other compile modes?  How portable can this be
-between engines?
+Compiles the `string` into a JavaScript function that takes zero arguments and
+returns the last expression.  This is run in global context
+with a file context of `path`, used in generating error stacktraces.
 
 ## Resources
 

test/fixtures/a.js

@@ -1 +1 @@
-return 'a'
+'a'

test/parallel/test-nucleus-compile.js

@@ -5,8 +5,8 @@ function assert(thing, message) {
   throw new Error(message)
 }
 
-var a = nucleus.compile("return 'a'", 'a')
+var a = nucleus.compile("'a'", 'a')
 assert(a() === 'a', "compile should return 'a'")
 
-var err = nucleus.compile("return new Error('oops')", 'test-nucleus-compile.js')
+var err = nucleus.compile("new Error('oops')", 'test-nucleus-compile.js')
 print(/\(test-nucleus-compile\.js:1\)/.test(err().stack), "nucleus must contain 'test-nucleus-compile.js'")

test/parallel/test-nucleus-readfile.js

@@ -4,6 +4,6 @@ function assert(thing, message) {
   throw new Error(message)
 }
 
-assert(nucleus.readfile('../fixtures/a.js') === "return 'a'\n", 'a.js must return it\'s raw source')
+assert(nucleus.readfile('../fixtures/a.js') === "'a'\n", 'a.js must return it\'s raw source')
 
 assert(nucleus.readfile('../fixtures/DOES-NOT-EXIST') === null, 'Non-existant file should return null')