Update src/System/Random.hs

Co-authored-by: Leonhard Markert <[email protected]>

src/System/Random.hs

@@ -189,7 +189,7 @@ genByteString n g = runStateGenST g (uniformByteStringM n)
 
 -- | The class of types for which random values can be generated. Most
 -- instances of `Random` will produce values that are uniformly distributed on the full
--- range, but for those types that such range cannot be determined some sensible default
+-- range, but for those types without a well-defined "full range" some sensible default
 -- subrange will be selected.
 --
 -- 'Random' exists primarily for backwards compatibility with version 1.1 of