… language has evolved in the service of particular human needs … what is really significant is that this functional principle is carried over and bu… - Michael Halliday

What makes learning possible is that the coding imposed by the mother tongue corresponds to a possible mode of perception and interpretation of the environment. A green car can be analysed experientially as carness qualified by greenness, if that is the way the system works.

Traditionally, grammar has always been a grammar of written language: and it has always been a product grammar" ['Product' is here used as one term of the Hjelmslevian pair process/product.] A process/product distinction is a relevant one for linguists because it corresponds to that between our experience of speech and our experience of writing: writing exists whereas speech happens.

The grammatical system has … a functional input and a structural output; it provides the mechanism for different functions to be combined in one utterance