The term FUNCTION is used in two distinct though related senses, at two very different points in the description of language. First, it is used in the sense of ʻgrammatical (or ʻsyntacticʼ) functionʼ, to refer to elements of linguistic structures such as actor and goal or subject and object or theme and rheme. The ʻfunctionsʼ are the roles occupied by classes of words, phrases and like in the structure of higher units. Secondly, it is used to refer to the ʻfunctionsʼ of language as a whole: for example in the well-known work of Karl Bühler in which he proposed a three-way division of language function into the representational, the conative and the expressive. Here I am using ʻfunctionʼ in the second sense; referring, however, not specifically to Bühler’s theory, but to the generalized notion of ʻfunctions of languageʼ.
- Halliday (1973), Pag. 104