fix minor bugs in dhallish.rb

docs.md

+# Documentation for Dhallish!
+
+*Dhallish* is a ruby gem and provides an executable dhallish. This executable reads from *STDIN* and
+outputs *JSON*. The *JSON* output does not aim to be compatible with [dhall-to-json](https://github.com/dhall-lang/dhall-haskell/tree/master/dhall-json).
+
+*dhallish* accepts the following command line options
+- '--pretty': print prettified json
+- '--type': print the type of the expression instead of its value
+
+If passed a file as a command line argument, *dhallish* reads from that file instead of stdin.
+
+*Dhallish* can also be used from other ruby files, if  './lib/dhallish.rb' is required from that file.
+The following functions from './lib/dhalish.rb' can be used:
+
+- `evaluate(dhallcode, ctx=nil, expected_type=nil)`:
+	Arguments:
+	- `dhallcode`: A string containing the expression that shall be evaluated
+	- `ctx`: The context in which the expression is evaluated. If nothing is passed, an empty context is used
+	- `expected_type`: The Dhallish-Type expected by the caller. If nothing is passed, a list is returned where
+		the first element is the value of the expression and the second element is the type.
+		If a Dhallish-Type is passed and the type of the result matches the expected type, only the value is returned.
+		If the passed type does not match the actual type, a DhallError is raised.
+
+- `create_ctx(dhallcode, basedir=Dir.pwd)`
+	Arguments:
+	- `dhallcode`: A string containing the expression that shall be evaluated
+	- `basedir`: A string containing a path that is used when files are imported from a relative path
+
+- `create_ctx_from_file(dhallfile, basedir=nil)`
+	Arguments
+	- `dhallfile`: A string containing the path to a file that contains dhallish-code
+	- `basedir`: A string containing a path that is used when files are imported from a relative path

lib/dhallish.rb

@@ -29,17 +29,17 @@ module Dhallish
 		if ctx.nil?; ctx = empty_context() end
 
 		rawast = @@parser.parse dhallcode
-		ast = rawast.to_node
-
-		if ast.nil?
-			raise DhallError, "#{@parser.failure_reason} (line/column: #{@parser.failure_line}:#{@parser.failure_column})"
+		if rawast.nil?
+			raise DhallError, "#{@@parser.failure_reason} (line/column: #{@@parser.failure_line}:#{@@parser.failure_column})"
 		end
 
+		ast = rawast.to_node
+
 		type = ast.compute_type ctx["<#TYPES#>"]
 		res = ast.evaluate ctx["<#VALS#>"]
 
 		if !expected_type.nil?
-			if type != expected_type
+			if !(type == expected_type)
 				raise DhallError, "expression return type missmatch: expected `#{expected_type}`, got: `#{type}`"
 			else
 				res