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inherent features of Int

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aarne
2006-04-04 14:44:46 +00:00
parent e059fddb6d
commit 0bffc3c9f6
6 changed files with 139 additions and 46 deletions
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doc/tutorial/gf-tutorial2.txt
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@@ -1539,7 +1539,7 @@ Here is an example of pattern matching, the paradigm of regular adjectives.
APl => fin + "a" ;
}
```
A constructor can have patterns as arguments. For instance,
A constructor can be used as a pattern that has patterns as arguments. For instance,
the adjectival paradigm in which the two singular forms are the same,
can be defined
```
@@ -1553,9 +1553,9 @@ can be defined
%--!
===Morphological analysis and morphology quiz===
Even though in GF morphology
is mostly seen as an auxiliary of syntax, a morphology once defined
can be used on its own right. The command ``morpho_analyse = ma``
Even though morphology is in GF
mostly used as an auxiliary for syntax, it
can also be useful on its own right. The command ``morpho_analyse = ma``
can be used to read a text and return for each word the analyses that
it has in the current concrete syntax.
```
@@ -1577,10 +1577,11 @@ the category is set to be something else than ``S``. For instance,
réapparaîtriez
Score 0/1
```
Finally, a list of morphological exercises and save it in a
Finally, a list of morphological exercises can be generated
off-line saved in a
file for later use, by the command ``morpho_list = ml``
```
> morpho_list -number=25 -cat=V
> morpho_list -number=25 -cat=V | wf exx.txt
```
The ``number`` flag gives the number of exercises generated.
@@ -1595,23 +1596,31 @@ verbs, such as //switch off//. The linearization of
a sentence may place the object between the verb and the particle:
//he switched it off//.
The first of the following judgements defines transitive verbs as
The following judgement defines transitive verbs as
**discontinuous constituents**, i.e. as having a linearization
type with two strings and not just one. The second judgement
type with two strings and not just one.
```
lincat TV = {s : Number => Str ; part : Str} ;
```
This linearization rule
shows how the constituents are separated by the object in complementization.
```
lincat TV = {s : Number => Str ; part : Str} ;
lin PredTV tv obj = {s = \\n => tv.s ! n ++ obj.s ++ tv.part} ;
```
There is no restriction in the number of discontinuous constituents
(or other fields) a ``lincat`` may contain. The only condition is that
the fields must be of finite types, i.e. built from records, tables,
parameters, and ``Str``, and not functions. A mathematical result
parameters, and ``Str``, and not functions.
A mathematical result
about parsing in GF says that the worst-case complexity of parsing
increases with the number of discontinuous constituents. Moreover,
the parsing and linearization commands only give reliable results
for categories whose linearization type has a unique ``Str`` valued
field labelled ``s``.
increases with the number of discontinuous constituents. This is
potentially a reason to avoid discontinuous constituents.
Moreover, the parsing and linearization commands only give accurate
results for categories whose linearization type has a unique ``Str``
valued field labelled ``s``. Therefore, discontinuous constituents
are not a good idea in top-level categories accessed by the users
of a grammar application.
%--!
@@ -1662,8 +1671,21 @@ can be used e.g. if a word lacks a certain form.
In general, ``variants`` should be used cautiously. It is not
recommended for modules aimed to be libraries, because the
user of the library has no way to choose among the variants.
Moreover, even though ``variants`` admits lists of any type,
its semantics for complex types can cause surprises.
Moreover, ``variants`` is only defined for basic types (``Str``
and parameter types). The grammar compiler will admit
``variants`` for any types, but it will push it to the
level of basic types in a way that may be unwanted.
For instance, German has two words meaning "car",
//Wagen//, which is Masculine, and //Auto//, which is Neuter.
However, if one writes
```
variants {{s = "Wagen" ; g = Masc} ; {s = "Auto" ; g = Neutr}}
```
this will compute to
```
{s = variants {"Wagen" ; "Auto"} ; g = variants {Masc ; Neutr}}
```
which will also accept erroneous combinations of strings and genders.
@@ -1736,12 +1758,8 @@ possible to write, slightly surprisingly,
%--!
===Regular expression patterns===
(New since 7 January 2006.)
To define string operations computed at compile time, such
as in morphology, it is handy to use regular expression patterns:
- //p// ``+`` //q// : token consisting of //p// followed by //q//
- //p// ``*`` : token //p// repeated 0 or more times
(max the length of the string to be matched)
@@ -1768,25 +1786,24 @@ Another example: English noun plural formation.
x + "y" => x + "ies" ;
_ => w + "s"
} ;
```
Semantics: variables are always bound to the **first match**, which is the first
in the sequence of binding lists ``Match p v`` defined as follows. In the definition,
``p`` is a pattern and ``v`` is a value.
```
Match (p1|p2) v = Match p1 v ++ Match p2 v
Match (p1+p2) s = [Match p1 s1 ++ Match p2 s2 | i <- [0..length s], (s1,s2) = splitAt i s]
Match p* s = Match "" s ++ Match p s ++ Match (p + p) s ++ ...
Match (p1+p2) s = [Match p1 s1 ++ Match p2 s2 |
i <- [0..length s], (s1,s2) = splitAt i s]
Match p* s = [[]] if Match "" s ++ Match p s ++ Match (p+p) s ++... /= []
Match -p v = [[]] if Match p v = []
Match c v = [[]] if c == v -- for constant and literal patterns c
Match x v = [[(x,v)]] -- for variable patterns x
Match x@p v = [[(x,v)]] + M if M = Match p v /= []
Match p v = [] otherwise -- failure
```
Examples:
- ``x + "e" + y`` matches ``"peter"`` with ``x = "p", y = "ter"``
- ``x@("foo"*)`` matches any token with ``x = ""``
- ``x + y@("er"*)`` matches ``"burgerer"`` with ``x = "burg", y = "erer"``
- ``x + "er"*`` matches ``"burgerer"`` with ``x = "burg"
@@ -1795,7 +1812,12 @@ Examples:
%--!
===Prefix-dependent choices===
The construct exemplified in
Sometimes a token has different forms depending on the token
that follows. An example is the English indefinite article,
which is //an// if a vowel follows, //a// otherwise.
Which form is chosen can only be decided at run time, i.e.
when a string is actually build. GF has a special construct for
such tokens, the ``pre`` construct exemplified in
```
oper artIndef : Str =
pre {"a" ; "an" / strs {"a" ; "e" ; "i" ; "o"}} ;
@@ -1837,6 +1859,47 @@ they can be used as arguments. For example:
```
==More concepts of abstract syntax==
===GF as a logical framework===
In this section, we will introduce concepts that make it possible
to encode advanced semantic concepts in an abstract syntax.
These concepts are inherited from **type theory**. Type theory
is the basis of many systems known as **logical frameworks**, which are
used for representing mathematical theorems and their proofs on a computer.
In fact, GF has a logical framework as its proper part:
this part is the abstract syntax.
In a logical framework, the formalization of a mathematical theory
is a set of type and function declarations. The following is an example
of such a theory, represented as an ``abstract`` module in GF.
```
abstract Geometry = {
cat
Line ; Point ; Circle ; -- basic types of figures
Prop ; -- proposition
fun
Parallel : Line -> Line -> Prop ; -- x is parallel to y
Centre : Circle -> Point ; -- the centre of c
}
```
===Dependent types===
===Higher-order abstract syntax===
===Semantic definitions===
===List categories===
%--!
==More features of the module system==
@@ -1891,18 +1954,6 @@ The rest of the modules (black) come from the resource.
==More concepts of abstract syntax==
===Dependent types===
===Higher-order abstract syntax===
===Semantic definitions===
===List categories===
==Transfer modules==
Transfer means noncompositional tree-transforming operations.