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diff --git a/doc/gf-reference.t2t b/doc/gf-reference.t2t deleted file mode 100644 index aab828f0a..000000000 --- a/doc/gf-reference.t2t +++ /dev/null @@ -1,493 +0,0 @@ -GF Quick Reference -Aarne Ranta -April 4, 2006 - -% NOTE: this is a txt2tags file. -% Create an html file from this file using: -% txt2tags -thtml gf-reference.t2t - -%!style:../css/style.css -%!target:html -%!options: --toc -%!postproc(html): <TITLE> <meta name = "viewport" content = "width = device-width"><TITLE> -%!postproc(html): <H1> <H1><a href="../"><IMG src="../doc/Logos/gf0.png"></a> - -This is a quick reference on GF grammars. It aims to -cover all forms of expression available when writing -grammars. It assumes basic knowledge of GF, which -can be acquired from the -[GF Tutorial http://www.grammaticalframework.org/doc/tutorial/gf-tutorial.html]. -Help on GF commands is obtained on line by the -help command (``help``), and help on invoking -GF with (``gf -help``). - - -===A complete example=== - -This is a complete example of a GF grammar divided -into three modules in files. The grammar recognizes the -phrases //one pizza// and //two pizzas//. - -File ``Order.gf``: -``` -abstract Order = { -cat - Order ; - Item ; -fun - One, Two : Item -> Order ; - Pizza : Item ; -} -``` -File ``OrderEng.gf`` (the top file): -``` ---# -path=.:prelude -concrete OrderEng of Order = - open Res, Prelude in { -flags startcat=Order ; -lincat - Order = SS ; - Item = {s : Num => Str} ; -lin - One it = ss ("one" ++ it.s ! Sg) ; - Two it = ss ("two" ++ it.s ! Pl) ; - Pizza = regNoun "pizza" ; -} -``` -File ``Res.gf``: -``` -resource Res = open Prelude in { -param Num = Sg | Pl ; -oper regNoun : Str -> {s : Num => Str} = - \dog -> {s = table { - Sg => dog ; - _ => dog + "s" - } - } ; -} -``` -To use this example, do -``` - % gf -- in shell: start GF - > i OrderEng.gf -- in GF: import grammar - > p "one pizza" -- parse string - > l Two Pizza -- linearize tree -``` - - - -===Modules and files=== - -One module per file. -File named ``Foo.gf`` contains module named -``Foo``. - -Each module has the structure -``` -moduletypename = - Inherits ** -- optional - open Opens in -- optional - { Judgements } -``` -Inherits are names of modules of the same type. -Inheritance can be restricted: -``` - Mo[f,g], -- inherit only f,g from Mo - Lo-[f,g] -- inheris all but f,g from Lo -``` -Opens are possible in ``concrete`` and ``resource``. -They are names of modules of these two types, possibly -qualified: -``` - (M = Mo), -- refer to f as M.f or Mo.f - (Lo = Lo) -- refer to f as Lo.f -``` -Module types and judgements in them: -``` -abstract A -- cat, fun, def, data -concrete C of A -- lincat, lin, lindef, printname -resource R -- param, oper - -interface I -- like resource, but can have - oper f : T without definition -instance J of I -- like resource, defines opers - that I leaves undefined -incomplete -- functor: concrete that opens - concrete CI of A = one or more interfaces - open I in ... -concrete CJ of A = -- completion: concrete that - CI with instantiates a functor by - (I = J) instances of open interfaces -``` -The forms -``param``, ``oper`` -may appear in ``concrete`` as well, but are then -not inherited to extensions. - -All modules can moreover have ``flags`` and comments. -Comments have the forms -``` --- till the end of line -{- any number of lines between -} ---# used for compiler pragmas -``` -A ``concrete`` can be opened like a ``resource``. -It is translated as follows: -``` -cat C ---> oper C : Type = -lincat C = T T ** {lock_C : {}} - -fun f : G -> C ---> oper f : A* -> C* = \g -> -lin f = t t g ** {lock_C = <>} -``` -An ``abstract`` can be opened like an ``interface``. -Any ``concrete`` of it then works as an ``instance``. - - - -===Judgements=== - -``` -cat C -- declare category C -cat C (x:A)(y:B x) -- dependent category C -cat C A B -- same as C (x : A)(y : B) -fun f : T -- declare function f of type T -def f = t -- define f as t -def f p q = t -- define f by pattern matching -data C = f | g -- set f,g as constructors of C -data f : A -> C -- same as - fun f : A -> C; data C=f - -lincat C = T -- define lin.type of cat C -lin f = t -- define lin. of fun f -lin f x y = t -- same as lin f = \x y -> t -lindef C = \s -> t -- default lin. of cat C -printname fun f = s -- printname shown in menus -printname cat C = s -- printname shown in menus -printname f = s -- same as printname fun f = s - -param P = C | D Q R -- define parameter type P - with constructors - C : P, D : Q -> R -> P -oper h : T = t -- define oper h of type T -oper h = t -- omit type, if inferrable - -flags p=v -- set value of flag p -``` -Judgements are terminated by semicolons (``;``). -Subsequent judgments of the same form may share the -keyword: -``` -cat C ; D ; -- same as cat C ; cat D ; -``` -Judgements can also share RHS: -``` -fun f,g : A -- same as fun f : A ; g : A -``` - - -===Types=== - -Abstract syntax (in ``fun``): -``` -C -- basic type, if cat C -C a b -- basic type for dep. category -(x : A) -> B -- dep. functions from A to B -(_ : A) -> B -- nondep. functions from A to B -(p,q : A) -> B -- same as (p : A)-> (q : A) -> B -A -> B -- same as (_ : A) -> B -Int -- predefined integer type -Float -- predefined float type -String -- predefined string type -``` -Concrete syntax (in ``lincat``): -``` -Str -- token lists -P -- parameter type, if param P -P => B -- table type, if P param. type -{s : Str ; p : P}-- record type -{s,t : Str} -- same as {s : Str ; t : Str} -{a : A} **{b : B}-- record type extension, same as - {a : A ; b : B} -A * B * C -- tuple type, same as - {p1 : A ; p2 : B ; p3 : C} -Ints n -- type of n first integers -``` -Resource (in ``oper``): all those of concrete, plus -``` -Tok -- tokens (subtype of Str) -A -> B -- functions from A to B -Int -- integers -Strs -- list of prefixes (for pre) -PType -- parameter type -Type -- any type -``` -As parameter types, one can use any finite type: -``P`` defined in ``param P``, -``Ints n``, and record types of parameter types. - - - -===Expressions=== - -Syntax trees = full function applications -``` -f a b -- : C if fun f : A -> B -> C -1977 -- : Int -3.14 -- : Float -"foo" -- : String -``` -Higher-Order Abstract syntax (HOAS): functions as arguments: -``` -F a (\x -> c) -- : C if a : A, c : C (x : B), - fun F : A -> (B -> C) -> C -``` -Tokens and token lists -``` -"hello" -- : Tok, singleton Str -"hello" ++ "world" -- : Str -["hello world"] -- : Str, same as "hello" ++ "world" -"hello" + "world" -- : Tok, computes to "helloworld" -[] -- : Str, empty list -``` -Parameters -``` -Sg -- atomic constructor -VPres Sg P2 -- applied constructor -{n = Sg ; p = P3} -- record of parameters -``` -Tables -``` -table { -- by full branches - Sg => "mouse" ; - Pl => "mice" - } -table { -- by pattern matching - Pl => "mice" ; - _ => "mouse" -- wildcard pattern - } -table { - n => regn n "cat" -- variable pattern - } -table Num {...} -- table given with arg. type -table ["ox"; "oxen"] -- table as course of values -\\_ => "fish" -- same as table {_ => "fish"} -\\p,q => t -- same as \\p => \\q => t - -t ! p -- select p from table t -case e of {...} -- same as table {...} ! e -``` -Records -``` -{s = "Liz"; g = Fem} -- record in full form -{s,t = "et"} -- same as {s = "et";t= "et"} -{s = "Liz"} ** -- record extension: same as - {g = Fem} {s = "Liz" ; g = Fem} - -<a,b,c> -- tuple, same as {p1=a;p2=b;p3=c} -``` -Functions -``` -\x -> t -- lambda abstract -\x,y -> t -- same as \x -> \y -> t -\x,_ -> t -- binding not in t -``` -Local definitions -``` -let x : A = d in t -- let definition -let x = d in t -- let defin, type inferred -let x=d ; y=e in t -- same as - let x=d in let y=e in t -let {...} in t -- same as let ... in t - -t where {...} -- same as let ... in t -``` -Free variation -``` -variants {x ; y} -- both x and y possible -variants {} -- nothing possible -``` -Prefix-dependent choices -``` -pre {"a" ; "an" / v} -- "an" before v, "a" otherw. -strs {"a" ; "i" ;"o"}-- list of condition prefixes -``` -Typed expression -``` -<t:T> -- same as t, to help type inference -``` -Accessing bound variables in ``lin``: use fields ``$1, $2, $3,...``. -Example: -``` -fun F : (A : Set) -> (El A -> Prop) -> Prop ; -lin F A B = {s = ["for all"] ++ A.s ++ B.$1 ++ B.s} -``` - - -===Pattern matching=== - -These patterns can be used in branches of ``table`` and -``case`` expressions. Patterns are matched in the order in -which they appear in the grammar. -``` -C -- atomic param constructor -C p q -- param constr. applied to patterns -x -- variable, matches anything -_ -- wildcard, matches anything -"foo" -- string -56 -- integer -{s = p ; y = q} -- record, matches extensions too -<p,q> -- tuple, same as {p1=p ; p2=q} -p | q -- disjunction, binds to first match -x@p -- binds x to what p matches -- p -- negation -p + "s" -- sequence of two string patterns -p* -- repetition of a string pattern -``` - -===Sample library functions=== - -``` --- lib/prelude/Predef.gf -drop : Int -> Tok -> Tok -- drop prefix of length -take : Int -> Tok -> Tok -- take prefix of length -tk : Int -> Tok -> Tok -- drop suffix of length -dp : Int -> Tok -> Tok -- take suffix of length -occur : Tok -> Tok -> PBool -- test if substring -occurs : Tok -> Tok -> PBool -- test if any char occurs -show : (P:Type) -> P ->Tok -- param to string -read : (P:Type) -> Tok-> P -- string to param -toStr : (L:Type) -> L ->Str -- find "first" string - --- lib/prelude/Prelude.gf -param Bool = True | False -oper - SS : Type -- the type {s : Str} - ss : Str -> SS -- construct SS - cc2 : (_,_ : SS) -> SS -- concat SS's - optStr : Str -> Str -- string or empty - strOpt : Str -> Str -- empty or string - bothWays : Str -> Str -> Str -- X++Y or Y++X - init : Tok -> Tok -- all but last char - last : Tok -> Tok -- last char - prefixSS : Str -> SS -> SS - postfixSS : Str -> SS -> SS - infixSS : Str -> SS -> SS -> SS - if_then_else : (A : Type) -> Bool -> A -> A -> A - if_then_Str : Bool -> Str -> Str -> Str -``` - - -===Flags=== - -Flags can appear, with growing priority, -- in files, judgement ``flags`` and without dash (``-``) -- as flags to ``gf`` when invoked, with dash -- as flags to various GF commands, with dash - - -Some common flags used in grammars: -``` -startcat=cat use this category as default - -lexer=literals int and string literals recognized -lexer=code like program code -lexer=text like text: spacing, capitals -lexer=textlit text, unknowns as string lits - -unlexer=code like program code -unlexer=codelit code, remove string lit quotes -unlexer=text like text: punctuation, capitals -unlexer=textlit text, remove string lit quotes -unlexer=concat remove all spaces -unlexer=bind remove spaces around "&+" - -optimize=all_subs best for almost any concrete -optimize=values good for lexicon concrete -optimize=all usually good for resource -optimize=noexpand for resource, if =all too big -``` -For the full set of values for ``FLAG``, -use on-line ``h -FLAG``. - - - -===File import search paths=== - -Colon-separated list of directories searched in the -given order: -``` ---# -path=.:../abstract:../common:prelude -``` -This can be (in order of increasing priority), as -first line in the file, as flag to ``gf`` -when invoked, or as flag to the ``i`` command. -The prefix ``--#`` is used only in files. - -GF attempts to satisfy an ``import`` command by searching for the -import filename in the above search paths, initially qualified -relative to the current working directory. If the file is not found in -that initial expansion, the search paths are re-qualified relative to -the directories given in the ``GF_LIB_PATH`` environment variable. If -``GF_LIB_PATH`` is not defined, its default value is -``/usr/local/share/gf-3.9/lib`` (assuming you have GF version 3.9). - -If your GF resource grammar libraries are installed somewhere else, -you will want to set ``GF_LIB_PATH`` to point there instead. In a -pinch, you can point to the ``GF/lib/src/`` folder in your clone of -the GF source code repository. - -Developers of resource grammars may find it useful to define multiple -directories, colon-separated, in ``GF_LIB_PATH``. - - -===Alternative grammar formats=== - -**Old GF** (before GF 2.0): -all judgements in any kinds of modules, -division into files uses ``include``s. -A file ``Foo.gf`` is recognized as the old format -if it lacks a module header. - -**Context-free** (file ``foo.cf``). The form of rules is e.g. -``` -Fun. S ::= NP "is" AP ; -``` -If ``Fun`` is omitted, it is generated automatically. -Rules must be one per line. The RHS can be empty. - -**Extended BNF** (file ``foo.ebnf``). The form of rules is e.g. -``` -S ::= (NP+ ("is" | "was") AP | V NP*) ; -``` -where the RHS is a regular expression of categories -and quoted tokens: ``"foo", CAT, T U, T|U, T*, T+, T?``, or empty. -Rule labels are generated automatically. - - -**Probabilistic grammars** (not a separate format). -You can set the probability of a function ``f`` (in its value category) by -``` ---# prob f 0.009 -``` -These are put into a file given to GF using the ``probs=File`` flag -on command line. This file can be the grammar file itself. - -**Example-based grammars** (file ``foo.gfe``). Expressions of the form -``` -in Cat "example string" -``` -are preprocessed by using a parser given by the flag -``` ---# -resource=File -``` -and the result is written to ``foo.gf``. - - -===References=== - -[GF Homepage http://www.grammaticalframework.org/] - -A. Ranta, Grammatical Framework: A Type-Theoretical Grammar Formalism. -//The Journal of Functional Programming//, vol. 14:2. 2004, pp. 145-189. - |