I posted a question about "Functionalist School of Lingustics".  I appreciate
all those who paid their attention to it.  They are:
 
I. FUNKNET
  mjschleppegrell@ucdavis.edu (Mary Schleppegrell)
  edwards@cogsci.Berkeley.EDU (Jane A. Edwards)
  TPAYNE@OREGON.UOREGON.EDU (Tom Payne)
  Wayne_Leman@sil.org (Wayne)
 
II. References
  tomlin@OREGON.UOREGON.EDU (Russell S. Tomlin)
  DUBARTELL@edinboro.edu (Deborah DuBartell)
  horning@jupiter.acs.oakland.edu (Alice Horning)
  mackenzi@jet.let.vu.nl (J.L. Mackenzie)
 
III. Answers
  Bert.Peeters@modlang.utas.edu.au (Bert Peeters)
  Mr Abbas Eslamy Rasekh (Abbas.Rasekh@arts.monash.edu.au)
  s-hilgen@uiuc.edu (Suzanne K. Hilgendorf)
  wignellp@NTU.EDU.AU (Peter Wignell)
  fcosws@firefly.prairienet.org (Steven Schaufele)
 
I. FUNKNET
I was told there's a net discussion group about functionalism.  It's FUNKNET.
To subscribe this group, send a letter to TGIVON@OREGON.UOREGON.EDU
(Tom Givon), instead of to the listserver.  For your reference, I quoted some
lines from the subscription response.
 
... Funknet is a loose
e-mail network for people who study various aspects of human language,
communication, cognition, socio-culture, neuro-psychology and other
facets of cognitive and communicative behavior....
The purpose of more explicit networks, such as FUNKNET, is to let
everybody know who is around, where they are, what they are working on,
what they are thinking of, and how we can share with, learn from, and
support each other.
 
II. References
 
Tomlin, R.  (1990).  Functionalism in SLA.  Studies in Second Language
Acquisition 12:155-177.
 
Suggested reading for a start:
Paul L. Garvin, Jan Firbas, Frantisek
Danes, Josef Vachek and Wilem Mathesius
 
A nice summary tracing this development of the functional approach is in
the 1985 dissertation by Margie Sue Berns from the University of Illinois:
"Functional Approaches and Communicative Competence: English Language
Teaching in Non-Native Contexts."  It also has been published as a book.
 
M.A.K Halliday.  Introduction to Functional Grammar. published by Edward Arnold,
 a
  British publisher in 1985.
 
Horning, Alice. The Psycholinguistics of Readable Writing
  It deals with the research of applied linguistics, including Halliday's work,
  published by Ablex Publishing, Norwood NJ, USA in 1993.
 
The work on FSP in rhetoric and composition studies has been done by William
Vande Kopple.  His work has been published in such American journals as:
1. College Composition and Communication,
2. the journal of the Conference on College Composition and Communication ( a
   sub-group of the National Council of Teachers of English in the USA.)
He is a faculty member at Hope College, in Holland, Michigan.
 
III. Answers (I've quoted and paraphrased the answers.)
My original query:
)1. Is there an unmovable fence for the definition of functional
) linguistics?
(Bert Peeters)
No. Well, most people would say there is probably a functional and a generative
definition. I think there are probably about as many definitions as there are
linguists who made attempts at defining language...
 
)2. Am I right that there are two aspects of defining language, functional
) and "?" ?
(Dr. Peeters)
The Prague school started it off. FSP is one if its contemporary
 manifestations.
It branched off into various directions. ( Martinet, English tradition with
Firth and Halliday.) Halliday developed "systemic functional grammar".
 
(Suzanne K. Hilgendorf)
 
The dichotomy you are referring to with regard to a perspective on language
is "formal" vs "functional" linguistics.
 
Parallel corresponding dichotomies are
"competence" vs. "performance"
"model-oriented" vs. "data-oriented"
"mentalistic" vs. "sociological/functional"
and in the United States "theoretical" vs "applied" linguistics.
 
Noam Chomsky's work and his transformational generative model is
representative for the "formal" approach, which dominates linguistic study
in the United States.
 
The functional approach comes from the British tradition and is considered
the basis for general linguistic study there.  In the United States, this
approach is sub-categorized as "sociolinguistics".
 
(Steven Schaufele)
As i see it, there are basically two ways of looking at language
('aspects' in the literal sense), which i would label 'formal' and
'functional'.  They parallel in some sense Saussure's dichotomy between
'signifiant' and 'signifie'.  Functional linguistics considers language
in regard to its relation to the outside world, the objective universe,
and therefore tends to focus on its functions, communicative and other-
 
wise, and tends to describe linguistic elements (morphemes, lexemes, syn-
tactic constructions, etc.) in terms of how they contribute to these
 
extralinguistic functions.  Formal linguistics, on the other hand, tends
to want to focus on the linguistic elements and constructions themselves,
as items of scientific interest, looking to find patterns within and
among these purely linguistic entities that lead to interesting and per-
spicuous descriptive accounts.
 
If i'm right, then what we have is not so much two distinct 'schools' of
linguistics as two rather amorphous 'ways of doing linguistic research',
with individual linguists plopping for one or the other, to varying
degrees, on the basis to a great extent of personal taste and/or philo-
sophical orientation.  In which case, no, there isn't any 'unmovable'
fence for the definition of either functional or formal linguistics.
Some theoretical approaches are more formal or functional than others; we
really have something like a spectrum.  Within the realm of syntactic
theory, where i am most knowledgeable, frameworks like Word Grammar and
Cognitive Grammar are extremely functionally oriented; frameworks like
Generalized Phrase-Structure Grammar and Chomskyan 'Standard' Theory
struggle to be as formal as possible (while occasionally being forced to
admit an irreduceable functionalist core in any complete description,
though Chomskyites tend to resist this temptation as much as possible);
and frameworks like Relational Grammar, Role & Reference Grammar,
Lexical-Functional Grammar, and Head-Driven Phrase-Structure Grammar
stake out intermediate areas of the continuum, combining both formal and
functional elements in their descriptions of syntactic phenomena.
 
)3. What's the hierarchical relationship between
)       functionalist school
)         prague school
)         English tradition
)         Firth
)         Halliday
)         FSP
)         FG
)         applied linguistics
 
(Suzanne K. Hilgendorf)
A sequential ordering by dates might help put things into perspective:
1) Prague School   1926
2) British tradition
2a) Firth (1890-1960) - Firthian linguistics, London School
2b) Halliday (1930?-) neo-Firthian, Systemic Linguistics
 
(Peter Wignell)
Halliday was Firth's student and both were influenced by the Prague school.
Both Halliday and Firth come from a European tradition (rather than
strictly British) influenced by Saussure (esp Halliday) (as was the prague
school to some extent).  What I'm saying is that there are influences
rather than hierarchies involved here.
As for applied linguistics.  My def is that any practical application of
any linguistic theory is 'applied linguistics'.  Halliday especially is
interested in the applications of his work (and that of colleagues) so
Systemic Functional Linguistics has an 'applied' orientation.