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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<META NAME="generator" CONTENT="http://txt2tags.sf.net">
<TITLE>GF Quick Reference</TITLE>
</HEAD><BODY BGCOLOR="white" TEXT="black">
<P ALIGN="center"><CENTER><H1>GF Quick Reference</H1>
<FONT SIZE="4">
<I>Aarne Ranta</I><BR>
Wed Mar 29 13:21:48 2006
</FONT></CENTER>
<P></P>
<HR NOSHADE SIZE=1>
<P></P>
<UL>
<LI><A HREF="#toc1">A Quick Example</A>
<LI><A HREF="#toc2">Modules and files</A>
<LI><A HREF="#toc3">Judgements</A>
<LI><A HREF="#toc4">Types</A>
<LI><A HREF="#toc5">Expressions</A>
<LI><A HREF="#toc6">Pattern matching</A>
<LI><A HREF="#toc7">Sample library functions</A>
<LI><A HREF="#toc8">Flags</A>
<LI><A HREF="#toc9">File paths</A>
<LI><A HREF="#toc10">Alternative grammar formats</A>
<LI><A HREF="#toc11">References</A>
</UL>
<P></P>
<HR NOSHADE SIZE=1>
<P></P>
<P>
This is a quick reference on GF grammars.
Help on GF commands is obtained on line by the
help command (<CODE>h</CODE>).
</P>
<A NAME="toc1"></A>
<H2>A Quick Example</H2>
<P>
This is a complete example, dividing a grammar
into three files.
</P>
<P>
<CODE>abstract</CODE>, <CODE>concrete</CODE>, and <CODE>resource</CODE>.
</P>
<P>
File <CODE>Order.gf</CODE>
</P>
<PRE>
abstract Order = {
cat
Order ;
Item ;
fun
One, Two : Item -&gt; Order ;
Pizza : Item ;
}
</PRE>
<P>
File <CODE>OrderEng.gf</CODE> (the top file):
</P>
<PRE>
--# -path=.:prelude
concrete OrderEng of Order =
open Res, Prelude in {
flags startcat=Order ;
lincat
Order = SS ;
Item = {s : Num =&gt; Str} ;
lin
One it = ss ("one" ++ it.s ! Sg) ;
Two it = ss ("two" ++ it.s ! Pl) ;
Pizza = regNoun "pizza" ;
}
</PRE>
<P>
File <CODE>Res.gf</CODE>:
</P>
<PRE>
resource Res = open Prelude in {
param Num = Sg | Pl ;
oper regNoun : Str -&gt; {s : Num =&gt; Str} =
\dog -&gt; {s = table {
Sg =&gt; dog ;
Pl =&gt; dog + "s"
}
} ;
}
</PRE>
<P>
To use this example, do
</P>
<PRE>
% gf -- in shell: start GF
&gt; i OrderEng.gf -- in GF: import grammar
&gt; p "one pizza" -- parse string
&gt; l Two Pizza -- linearize tree
</PRE>
<P></P>
<A NAME="toc2"></A>
<H2>Modules and files</H2>
<P>
One module per file.
File named <CODE>Foo.gf</CODE> contains module named
<CODE>Foo</CODE>.
</P>
<P>
Each module has the structure
</P>
<PRE>
moduletypename =
Inherits ** -- optional
open Opens in -- optional
{ Judgements }
</PRE>
<P>
Inherits are names of modules of the same type.
Inheritance can be restricted:
</P>
<PRE>
Mo[f,g], -- inherit only f,g from Mo
Lo-[f,g] -- inheris all but f,g from Lo
</PRE>
<P>
Opens are possible in <CODE>concrete</CODE> and <CODE>resource</CODE>.
They are names of modules of these two types, possibly
qualified:
</P>
<PRE>
(M = Mo), -- refer to f as M.f or Mo.f
(Lo = Lo) -- refer to f as Lo.f
</PRE>
<P>
Module types and judgements in them:
</P>
<PRE>
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
</PRE>
<P>
The forms
<CODE>param</CODE>, <CODE>oper</CODE>
may appear in <CODE>concrete</CODE> as well, but are then
not inherited to extensions.
</P>
<P>
All modules can moreover have <CODE>flags</CODE> and comments.
Comments have the forms
</P>
<PRE>
-- till the end of line
{- any number of lines between -}
--# reserved for compiler pragmas
</PRE>
<P>
A <CODE>concrete</CODE> can be opened like a <CODE>resource</CODE>.
It is translated as follows:
</P>
<PRE>
cat C ---&gt; oper C : Type =
lincat C = T T ** {lock_C : {}}
fun f : G -&gt; C ---&gt; oper f : A* -&gt; C* = \g -&gt;
lin f = t t g ** {lock_C = &lt;&gt;}
</PRE>
<P>
An <CODE>abstract</CODE> can be opened like an <CODE>interface</CODE>.
Any <CODE>concrete</CODE> of it then works as an <CODE>instance</CODE>.
</P>
<A NAME="toc3"></A>
<H2>Judgements</H2>
<PRE>
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 -&gt; C -- same as
fun f : A -&gt; 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 -&gt; t
lindef C = \s -&gt; 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 -&gt; R -&gt; 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
</PRE>
<P>
Judgements are terminated by semicolons (<CODE>;</CODE>).
Subsequent judgments of the same form may share the
keyword:
</P>
<PRE>
cat C ; D ; -- same as cat C ; cat D ;
</PRE>
<P>
Judgements can also share RHS:
</P>
<PRE>
fun f,g : A -- same as fun f : A ; g : A
</PRE>
<P></P>
<A NAME="toc4"></A>
<H2>Types</H2>
<P>
Abstract syntax (in <CODE>fun</CODE>):
</P>
<PRE>
C -- basic type, if cat C
C a b -- basic type for dep. category
(x : A) -&gt; B -- dep. functions from A to B
(_ : A) -&gt; B -- nondep. functions from A to B
(p,q : A) -&gt; B -- same as (p : A)-&gt; (q : A) -&gt; B
A -&gt; B -- same as (_ : A) -&gt; B
Int -- predefined integer type
Float -- predefined float type
String -- predefined string type
</PRE>
<P>
Concrete syntax (in <CODE>lincat</CODE>):
</P>
<PRE>
Str -- token lists
P -- parameter type, if param P
P =&gt; 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
</PRE>
<P>
Resource (in <CODE>oper</CODE>): all those of concrete, plus
</P>
<PRE>
Tok -- tokens (subset of Str)
A -&gt; B -- functions from A to B
Int -- integers
Strs -- list of prefixes (for pre)
PType -- parameter type
Type -- any type
</PRE>
<P>
As parameter types, one can use any finite type:
<CODE>param</CODE> constants <CODE>P</CODE>,
<CODE>Ints n</CODE>, and record types of parameter types.
</P>
<A NAME="toc5"></A>
<H2>Expressions</H2>
<P>
Syntax trees = full function applications
</P>
<PRE>
f a b -- : C if fun f : A -&gt; B -&gt; C
1977 -- : Int
3.14 -- : Float
"foo" -- : String
</PRE>
<P>
Higher-Order Abstract syntax (HOAS): functions as arguments:
</P>
<PRE>
F a (\y -&gt; b) -- : C if a : A, b : B (x : A),
fun F : A -&gt; (B -&gt; C) -&gt; C
</PRE>
<P>
Tokens and token lists
</P>
<PRE>
"hello" -- : Tok, singleton Str
"hello" ++ "world" -- : Str
["hello world"] -- : Str, same as "hello" ++ "world"
"hello" + "world" -- : Tok, computes to "helloworld"
[] -- : Str, empty list
</PRE>
<P>
Parameters
</P>
<PRE>
Sg -- atomic constructor
VPres Sg P2 -- applied constructor
{n = Sg ; p = P3} -- record of parameters
</PRE>
<P>
Tables
</P>
<PRE>
table { -- by full branches
Sg =&gt; "mouse" ;
Pl =&gt; "mice"
}
table { -- by pattern matching
Pl =&gt; "mice" ;
_ =&gt; "mouse" -- wildcard pattern
}
table {
n =&gt; regn n "cat" ;-- variable pattern
}
table Num {...} -- table given with arg. type
table ["ox"; "oxen"] -- table as course of values
\\_ =&gt; "fish" -- same as table {_ =&gt; "fish"}
\\p,q =&gt; t -- same as \\p =&gt; \\q =&gt; t
t ! p -- select p from table t
case e of {...} -- same as table {...} ! e
</PRE>
<P>
Records
</P>
<PRE>
{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}
&lt;a,b,c&gt; -- tuple, same as {p1=a;p2=b;p3=c}
</PRE>
<P>
Functions
</P>
<PRE>
\x -&gt; t -- lambda abstract
\x,y -&gt; t -- same as \x -&gt; \y -&gt; t
\x,_ -&gt; t -- binding not in t
</PRE>
<P>
Local definitions
</P>
<PRE>
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
</PRE>
<P>
Free variation
</P>
<PRE>
variants {x ; y} -- both x and y possible
variants {} -- nothing possible
</PRE>
<P>
Prefix-dependent choices
</P>
<PRE>
pre {"a" ; "an" / v} -- "an" before v, "a" otherw.
strs {"a" ; "i" ;"o"}-- list of condition prefixes
</PRE>
<P>
Typed expression
</P>
<PRE>
&lt;t:T&gt; -- same as t, to help type inference
</PRE>
<P>
Accessing bound variables in <CODE>lin</CODE>: use fields <CODE>$1, $2, $3,...</CODE>.
Example:
</P>
<PRE>
fun F : (A : Set) -&gt; (El A -&gt; Prop) -&gt; Prop ;
lin F A B = {s = ["for all"] ++ A.s ++ B.$1 ++ B.s}
</PRE>
<P></P>
<A NAME="toc6"></A>
<H2>Pattern matching</H2>
<P>
These patterns can be used in branches of <CODE>table</CODE> and
<CODE>case</CODE> expressions.
</P>
<PRE>
C -- atomic param constructor
C p q -- param constr. appl- to patterns
x -- variable, matches anything
_ -- wildcard, matches anything
"foo" -- string
56 -- integer
{s = p ; y = q} -- record, matches extensions too
&lt;p,q&gt; -- 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
</PRE>
<P></P>
<A NAME="toc7"></A>
<H2>Sample library functions</H2>
<PRE>
-- lib/prelude/Predef.gf
drop : Int -&gt; Tok -&gt; Tok -- drop prefix of length
take : Int -&gt; Tok -&gt; Tok -- take prefix of length
tk : Int -&gt; Tok -&gt; Tok -- drop suffix of length
dp : Int -&gt; Tok -&gt; Tok -- take suffix of length
occur : Tok -&gt; Tok -&gt; PBool -- test if substring
occurs : Tok -&gt; Tok -&gt; PBool -- test if any char occurs
show : (P:Type) -&gt; P -&gt;Tok -- param to string
read : (P:Type) -&gt; Tok-&gt; P -- string to param
toStr : (L:Type) -&gt; L -&gt;Str -- find "first" string
-- lib/prelude/Prelude.gf
param Bool = True | False
oper
SS : Type -- the type {s : Str}
ss : Str -&gt; SS -- construct SS
cc2 : (_,_ : SS) -&gt; SS -- concat SS's
optStr : Str -&gt; Str -- string or empty
strOpt : Str -&gt; Str -- empty or string
bothWays : Str -&gt; Str -&gt; Str -- X++Y or Y++X
init : Tok -&gt; Tok -- all but last char
last : Tok -&gt; Tok -- last char
prefixSS : Str -&gt; SS -&gt; SS
postfixSS : Str -&gt; SS -&gt; SS
infixSS : Str -&gt; SS -&gt; SS -&gt; SS
if_then_else : (A : Type) -&gt; Bool -&gt; A -&gt; A -&gt; A
if_then_Str : Bool -&gt; Str -&gt; Str -&gt; Str
</PRE>
<P></P>
<A NAME="toc8"></A>
<H2>Flags</H2>
<P>
Flags can appear, with growing priority,
</P>
<UL>
<LI>in files, judgement <CODE>flags</CODE> and without dash (<CODE>-</CODE>)
<LI>as flags to <CODE>gf</CODE> when invoked, with dash
<LI>as flags to various GF commands, with dash
</UL>
<P>
Some common flags used in grammars:
</P>
<PRE>
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 "&amp;+"
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
</PRE>
<P>
For the full set of values for <CODE>flag</CODE>,
use on-line <CODE>h -flag</CODE>.
</P>
<A NAME="toc9"></A>
<H2>File paths</H2>
<P>
Colon-separated lists of directories tried in the
given order:
</P>
<PRE>
--# -path=.:../abstract:../common:prelude
</PRE>
<P>
This can be (in order of growing preference), as
first line in the top file, as flag to <CODE>gf</CODE>
when invoked, or as flag to the <CODE>i</CODE> command.
The prefix <CODE>--#</CODE> is used only in files.
</P>
<P>
If the variabls <CODE>GF_LIB_PATH</CODE> is defined, its
value is automatically prefixed to each directory to
extend the original search path.
</P>
<A NAME="toc10"></A>
<H2>Alternative grammar formats</H2>
<P>
<B>Old GF</B> (before GF 2.0):
all judgements in any kinds of modules,
division into files uses <CODE>include</CODE>s.
A file <CODE>Foo.gf</CODE> is recognized as the old format
if it lacks a module header.
</P>
<P>
<B>Context-free</B> (file <CODE>foo.cf</CODE>). The form of rules is e.g.
</P>
<PRE>
Fun. S ::= NP "is" AP ;
</PRE>
<P>
If <CODE>Fun</CODE> is omitted, it is generated automatically.
Rules must be one per line. The RHS can be empty.
</P>
<P>
<B>Extended BNF</B> (file <CODE>foo.ebnf</CODE>). The form of rules is e.g.
</P>
<PRE>
S ::= (NP+ ("is" | "was") AP | V NP*) ;
</PRE>
<P>
where the RHS is a regular expression of categories
and quoted tokens: <CODE>"foo", T U, T|U, T*, T+, T?</CODE>, or empty.
Rule labels are generated automatically.
</P>
<P>
<B>Probabilistic grammars</B> (not a separate format).
You can set the probability of a function <CODE>f</CODE> (in its value category) by
</P>
<PRE>
--# prob f 0.009
</PRE>
<P>
These are put into a file given to GF using the <CODE>probs=File</CODE> flag
on command line. This file can be the grammar file itself.
</P>
<P>
<B>Example-based grammars</B> (file <CODE>foo.gfe</CODE>). Expressions of the form
</P>
<PRE>
in Cat "example string"
</PRE>
<P>
are preprocessed by using a parser given by the flag
</P>
<PRE>
--# -resource=File
</PRE>
<P>
and the result is written to <CODE>foo.gf</CODE>.
</P>
<A NAME="toc11"></A>
<H2>References</H2>
<P>
<A HREF="http://www.cs.chalmers.se/~aarne/GF/">GF Homepage</A>
</P>
<P>
A. Ranta, Grammatical Framework: A Type-Theoretical Grammar Formalism.
<I>The Journal of Functional Programming</I>, vol. 14:2. 2004, pp. 145-189.
</P>
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@@ -16,41 +16,48 @@ help command (``h``).
==A Quick Example==
This is a complete example using
This is a complete example, dividing a grammar
into three files.
``abstract``, ``concrete``, and ``resource``.
File ``Order.gf``
```
-- in file Order.gf
abstract Order = {
cat
Order ;
Item ;
fun
One, Two : Item -> Order ;
Pizza : Item ;
}
-- in file OrderEng.gf
concrete OrderEng of Order = open Res in {
flags startcat=Order ;
cat
Order = {s : Str} ;
Item = {s : Num => Str} ;
fun
One it = {s = "one" ++ it.s ! Sg} ;
Two it = {s = "two" ++ it.s ! Pl} ;
Pizza = regNoun "pizza" ;
}
-- in file Res.gf
resource Res = {
param Num = Sg | Pl ;
oper regNoun : Str -> {s : Num => Str} =
\dog -> {s = table {
Sg => dog ;
Pl => dog + "s"
}
} ;
} ;
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 ;
Pl => dog + "s"
}
} ;
}
```
To use this example, do
```
@@ -64,29 +71,29 @@ To use this example, do
==Modules and files==
In standard GF, there is one module per file.
One module per file.
File named ``Foo.gf`` contains module named
``Foo``.
Each module has the structure
```
moduletypename =
Extends ** -- optional
open Opens in -- optional
Inherits ** -- optional
open Opens in -- optional
{ Judgements }
```
Extends are names of modules of the same type.
They can be restricted:
Inherits are names of modules of the same type.
Inheritance can be restricted:
```
Mo[f,g], -- inherit only f,g
Lo-[f,g] -- inheris all but f,g
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), -- references M.f or Mo.f
(Lo = Lo) -- references Lo.f
(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:
```
@@ -95,23 +102,28 @@ concrete C of A -- lincat, lin, lindef, printname
resource R -- param, oper
interface I -- like resource, but can have
-- oper f : T without definition
oper f : T without definition
instance J of I -- like resource, defines opers
-- that I leaves undefined
that I leaves undefined
incomplete -- functor: concrete that opens
concrete CI of A = -- one or more interfaces
concrete CI of A = one or more interfaces
open I in ...
concrete CJ of A = -- completion: concrete that
CI with -- instantiates a functor by giving
(I = J) -- instances of its open interfaces
CI with instantiates a functor by
(I = J) instances of open interfaces
```
The forms
``param``, ``oper``
may appear in ``concrete`` as well, but are not inherited to
extensions.
All modules can moreover have ``flag``s.
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 -}
--# reserved for compiler pragmas
```
A ``concrete`` can be opened like a ``resource``.
It is translated as follows:
```
@@ -130,13 +142,14 @@ Any ``concrete`` of it then works as an ``instance``.
```
cat C -- declare category C
cat C (x : A) -- dependent category C
cat C A -- same as C (x : A)
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 -- set f as constructor of C
data f : A -> C -- same as fun f : A; data C=f
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
@@ -146,15 +159,16 @@ 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 ptype P with constrs
-- C : P, D : Q -> R -> P
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
flag p=v -- define value of flag p
flags p=v -- set value of flag p
```
Judgements are terminated by semicolons (``;``).
Subsequent judgments of the same form may share their
Subsequent judgments of the same form may share the
keyword:
```
cat C ; D ; -- same as cat C ; cat D ;
@@ -187,9 +201,9 @@ 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 : A ; b : B}
A * B * C -- tuple type, same as
-- {p1 : A ; p2 : B ; p3 : C}
{p1 : A ; p2 : B ; p3 : C}
Ints n -- type of n first integers
```
Resource (in ``oper``): all those of concrete, plus
@@ -197,7 +211,7 @@ Resource (in ``oper``): all those of concrete, plus
Tok -- tokens (subset of Str)
A -> B -- functions from A to B
Int -- integers
Strs -- list of prefixes
Strs -- list of prefixes (for pre)
PType -- parameter type
Type -- any type
```
@@ -219,14 +233,14 @@ f a b -- : C if fun f : A -> B -> C
Higher-Order Abstract syntax (HOAS): functions as arguments:
```
F a (\y -> b) -- : C if a : A, b : B (x : A),
-- fun F : A -> (B -> C) -> C
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" -- : Str, computes to "helloworld"
"hello" + "world" -- : Tok, computes to "helloworld"
[] -- : Str, empty list
```
Parameters
@@ -248,24 +262,21 @@ table { -- by pattern matching
table {
n => regn n "cat" ;-- variable pattern
}
\\_ => "fish" -- same as table {n => "fish"}
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
table Num [ -- table given with arg. type
"mouse" ; "mice" -- and course of values
]
t ! p -- select p from table t
case e of {...} -- same as table {...} ! e
```
Records
```
{s = "Liz" ; g = Fem}-- record in full form
{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}
{g = Fem} {s = "Liz" ; g = Fem}
<a,b,c> -- tuple, same as {p1=a;p2=b;p3=c}
```
@@ -273,13 +284,14 @@ 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=t in d
let x=d in let y=e in t
let {...} in t -- same as let ... in t
t where {...} -- same as let ... in t
@@ -298,10 +310,11 @@ Typed expression
```
<t:T> -- same as t, to help type inference
```
Accessing bound variables in HOAS: use fields ``$1, $2, $3,...``.
Accessing bound variables in ``lin``: use fields ``$1, $2, $3,...``.
Example:
```
lin F a b = {s = ["for all"] ++ a.s ++ b.$1 ++ b.s}
fun F : (A : Set) -> (El A -> Prop) -> Prop ;
lin F A B = {s = ["for all"] ++ A.s ++ B.$1 ++ B.s}
```
@@ -329,15 +342,15 @@ p* -- repetition of a string pattern
```
-- 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
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
@@ -347,7 +360,7 @@ oper
cc2 : (_,_ : SS) -> SS -- concat SS's
optStr : Str -> Str -- string or empty
strOpt : Str -> Str -- empty or string
bothWays : Str -> Str -> Str -- XY or YX
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
@@ -361,8 +374,7 @@ oper
==Flags==
Flags can appear, with growing priority,
- in files, with judgement keyword ``flags``
and without dash (``-``)
- in files, judgement ``flags`` and without dash (``-``)
- as flags to ``gf`` when invoked, with dash
- as flags to various GF commands, with dash
@@ -383,18 +395,19 @@ unlexer=textlit text, remove string lit quotes
unlexer=concat remove all spaces
unlexer=bind remove spaces around "&+"
optimize=values good for lexicon concrete
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 flags, use on-line ``h -flag``.
For the full set of values for ``flag``,
use on-line ``h -flag``.
==File paths==
Colon-separated lists of search directories tried in the
Colon-separated lists of directories tried in the
given order:
```
--# -path=.:../abstract:../common:prelude
@@ -417,23 +430,19 @@ 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
**Context-free** (file ``foo.cf``). The form of rules is e.g.
```
Fun. Cat ::= Cat "tok" Cat ;
Fun. S ::= NP "is" AP ;
```
where ``Fun`` is optional. Rules must be one per line.
The RHS can be empty.
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
**Extended BNF** (file ``foo.ebnf``). The form of rules is e.g.
```
Cat ::= Reg ;
S ::= (NP+ ("is" | "was") AP | V NP*) ;
```
where ``Reg`` is a regular expression of categories
and quoted tokens:
```
T U, T|U, T*, T+, T?
```
The RHS can also be empty.
where the RHS is a regular expression of categories
and quoted tokens: ``"foo", T U, T|U, T*, T+, T?``, or empty.
Rule labels are generated automatically.
@@ -447,11 +456,11 @@ on command line. This file can be the grammar file itself.
**Example-based grammars** (file ``foo.gfe``). Expressions of the form
```
in Mo.Cat "example string"
in Cat "example string"
```
are preprocessed by using a parser given by the flag
```
--# resource=File
--# -resource=File
```
and the result is written to ``foo.gf``.