Here is a typical conditional sentence. Instead of using if…not, it is possible to use this construction. Here, the word unless has the same meaning as if…not. This is commonly used in academic writing and reading texts. Notice that when you use unless, the verb is no longer negative. Now consider this conditional sentence. Provided that can be used to replace ‘if’. It literally means ‘on condition that’. Providing that and as long as have the same meaning, although as long as is less formal than provided or providing.