From 84adefa331c4159d432d22840663c38f155cd4c1 Mon Sep 17 00:00:00 2001 From: Erlang/OTP Date: Fri, 20 Nov 2009 14:54:40 +0000 Subject: The R13B03 release. --- system/doc/programming_examples/Makefile | 98 ++++ system/doc/programming_examples/bit_syntax.xml | 327 +++++++++++++ system/doc/programming_examples/book.xml | 37 ++ system/doc/programming_examples/fun_test.erl | 17 + system/doc/programming_examples/funparse.erl | 74 +++ system/doc/programming_examples/funs.xmlsrc | 515 +++++++++++++++++++++ system/doc/programming_examples/funs1.erl | 125 +++++ .../programming_examples/list_comprehensions.xml | 206 +++++++++ system/doc/programming_examples/make.dep | 20 + system/doc/programming_examples/part.xml | 39 ++ system/doc/programming_examples/records.xml | 232 ++++++++++ system/doc/programming_examples/xmlfiles.mk | 23 + 12 files changed, 1713 insertions(+) create mode 100644 system/doc/programming_examples/Makefile create mode 100644 system/doc/programming_examples/bit_syntax.xml create mode 100644 system/doc/programming_examples/book.xml create mode 100644 system/doc/programming_examples/fun_test.erl create mode 100644 system/doc/programming_examples/funparse.erl create mode 100644 system/doc/programming_examples/funs.xmlsrc create mode 100644 system/doc/programming_examples/funs1.erl create mode 100644 system/doc/programming_examples/list_comprehensions.xml create mode 100644 system/doc/programming_examples/make.dep create mode 100644 system/doc/programming_examples/part.xml create mode 100644 system/doc/programming_examples/records.xml create mode 100644 system/doc/programming_examples/xmlfiles.mk (limited to 'system/doc/programming_examples') diff --git a/system/doc/programming_examples/Makefile b/system/doc/programming_examples/Makefile new file mode 100644 index 0000000000..73512c9654 --- /dev/null +++ b/system/doc/programming_examples/Makefile @@ -0,0 +1,98 @@ +# +# %CopyrightBegin% +# +# Copyright Ericsson AB 2003-2009. All Rights Reserved. +# +# The contents of this file are subject to the Erlang Public License, +# Version 1.1, (the "License"); you may not use this file except in +# compliance with the License. You should have received a copy of the +# Erlang Public License along with this software. If not, it can be +# retrieved online at http://www.erlang.org/. +# +# Software distributed under the License is distributed on an "AS IS" +# basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See +# the License for the specific language governing rights and limitations +# under the License. +# +# %CopyrightEnd% +# +# +include $(ERL_TOP)/make/target.mk +include $(ERL_TOP)/make/$(TARGET)/otp.mk + +# ---------------------------------------------------- +# Application version +# ---------------------------------------------------- +include $(ERL_TOP)/erts/vsn.mk +#VSN=$(SYSTEM_VSN) + +APPLICATION=otp-system-documentation +# ---------------------------------------------------- +# Release directory specification +# ---------------------------------------------------- +RELSYSDIR = $(RELEASE_PATH)/doc/programming_examples + +# ---------------------------------------------------- +# Target Specs +# ---------------------------------------------------- +XML_PART_FILES = part.xml + +include xmlfiles.mk + +XML_CHAPTER_FILES=$(PROG_EX_CHAPTER_FILES) + +TOPDOCDIR=.. + +BOOK_FILES = book.xml + +GIF_FILES = + +PS_FILES = + +XML_FILES = \ + $(BOOK_FILES) $(XML_CHAPTER_FILES) \ + $(XML_PART_FILES) +# ---------------------------------------------------- + +HTML_FILES = \ + $(XML_PART_FILES:%.xml=%.html) + +HTMLDIR = ../html/programming_examples + +HTML_UG_FILE = $(HTMLDIR)/users_guide.html + +# ---------------------------------------------------- +# FLAGS +# ---------------------------------------------------- +XML_FLAGS += +DVIPS_FLAGS += + +# ---------------------------------------------------- +# Targets +# ---------------------------------------------------- +docs: html +local_docs: PDFDIR=../../pdf + +html: $(GIF_FILES) $(HTML_UG_FILE) + +debug opt: + +clean clean_docs: + rm -rf $(HTMLDIR) + rm -f $(TOP_PDF_FILE) $(TOP_PDF_FILE:%.pdf=%.fo) + rm -f errs core *~ + +# ---------------------------------------------------- +# Release Target +# ---------------------------------------------------- +include $(ERL_TOP)/make/otp_release_targets.mk + +release_docs_spec: docs + $(INSTALL_DIR) $(RELSYSDIR) + $(INSTALL_DATA) $(GIF_FILES) $(HTMLDIR)/*.html \ + $(RELSYSDIR) + +release_spec: + + + diff --git a/system/doc/programming_examples/bit_syntax.xml b/system/doc/programming_examples/bit_syntax.xml new file mode 100644 index 0000000000..3306365c0e --- /dev/null +++ b/system/doc/programming_examples/bit_syntax.xml @@ -0,0 +1,327 @@ + + + + +
+ + 20032009 + Ericsson AB. All Rights Reserved. + + + The contents of this file are subject to the Erlang Public License, + Version 1.1, (the "License"); you may not use this file except in + compliance with the License. You should have received a copy of the + Erlang Public License along with this software. If not, it can be + retrieved online at http://www.erlang.org/. + + Software distributed under the License is distributed on an "AS IS" + basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See + the License for the specific language governing rights and limitations + under the License. + + + + Bit Syntax + + + + + bit_syntax.xml +
+ +
+ Introduction +

In Erlang a Bin is used for constructing binaries and matching + binary patterns. A Bin is written with the following syntax:

+ >]]> +

A Bin is a low-level sequence of bits or bytes. The purpose of a Bin is + to be able to, from a high level, construct a binary,

+ >]]> +

in which case all elements must be bound, or to match a binary,

+ > = Bin ]]> +

where Bin is bound, and where the elements are bound or + unbound, as in any match.

+

In R12B, a Bin need not consist of a whole number of bytes.

+ +

A bitstring is a sequence of zero or more bits, where + the number of bits doesn't need to be divisible by 8. If the number + of bits is divisible by 8, the bitstring is also a binary.

+

Each element specifies a certain segment of the bitstring. + A segment is a set of contiguous bits of the binary (not + necessarily on a byte boundary). The first element specifies + the initial segment, the second element specifies the following + segment etc.

+

The following examples illustrate how binaries are constructed + or matched, and how elements and tails are specified.

+ +
+ Examples +

Example 1: A binary can be constructed from a set of + constants or a string literal:

+ >, +Bin12 = <<"abc">>]]> +

yields binaries of size 3; binary_to_list(Bin11) + evaluates to [1, 17, 42], and + binary_to_list(Bin12) evaluates to [97, 98, 99].

+

Example 2: Similarly, a binary can be constructed + from a set of bound variables:

+ >]]> +

yields a binary of size 4, and binary_to_list(Bin2) + evaluates to [1, 17, 00, 42] too. Here we used a + size expression for the variable C in order to + specify a 16-bits segment of Bin2.

+

Example 3: A Bin can also be used for matching: if + D, E, and F are unbound variables, and + Bin2 is bound as in the former example,

+ > = Bin2]]> +

yields D = 273, E = 00, and F binds to a binary + of size 1: binary_to_list(F) = [42].

+

Example 4: The following is a more elaborate example + of matching, where Dgram is bound to the consecutive + bytes of an IP datagram of IP protocol version 4, and where we + want to extract the header and the data of the datagram:

+ > when HLen>=5, 4*HLen= + OptsLen = 4*(HLen - ?IP_MIN_HDR_LEN), + <> = RestDgram, + ... +end.]]> +

Here the segment corresponding to the Opts variable + has a type modifier specifying that Opts should + bind to a binary. All other variables have the default type + equal to unsigned integer.

+

An IP datagram header is of variable length, and its length - + measured in the number of 32-bit words - is given in + the segment corresponding to HLen, the minimum value of + which is 5. It is the segment corresponding to Opts + that is variable: if HLen is equal to 5, Opts + will be an empty binary.

+

The tail variables RestDgram and Data bind to + binaries, as all tail variables do. Both may bind to empty + binaries.

+

If the first 4-bits segment of Dgram is not equal to + 4, or if HLen is less than 5, or if the size of + Dgram is less than 4*HLen, the match of + Dgram fails.

+
+
+ +
+ A Lexical Note +

Note that ">]]>" will be interpreted as + ">]]>", which is a syntax error. + The correct way to write the expression is + ">]]>".

+
+ +
+ Segments +

Each segment has the following general syntax:

+

Value:Size/TypeSpecifierList

+

Both the Size and the TypeSpecifier or both may be + omitted; thus the following variations are allowed:

+

Value

+

Value:Size

+

Value/TypeSpecifierList

+

Default values will be used for missing specifications. + The default values are described in the section + Defaults.

+

Used in binary construction, the Value part is any + expression. Used in binary matching, the Value part must + be a literal or variable. You can read more about + the Value part in the section about constructing + binaries and matching binaries.

+

The Size part of the segment multiplied by the unit in + the TypeSpecifierList (described below) gives the number + of bits for the segment. In construction, Size is any + expression that evaluates to an integer. In matching, + Size must be a constant expression or a variable.

+

The TypeSpecifierList is a list of type specifiers + separated by hyphens.

+ + Type + The type can be integer, float, or + binary. + Signedness + The signedness specification can be either signed + or unsigned. Note that signedness only matters for + matching. + Endianness + The endianness specification can be either big, + little, or native. Native-endian means that + the endian will be resolved at load time to be either + big-endian or little-endian, depending on what is "native" + for the CPU that the Erlang machine is run on. + Unit + The unit size is given as unit:IntegerLiteral. + The allowed range is 1-256. It will be multiplied by + the Size specifier to give the effective size of + the segment. In R12B, the unit size specifies the alignment + for binary segments without size (examples will follow). + +

Example:

+ +X:4/little-signed-integer-unit:8 +

This element has a total size of 4*8 = 32 bits, and it contains + a signed integer in little-endian order.

+
+ +
+ Defaults +

The default type for a segment is integer. The default + type does not depend on the value, even if the value is a + literal. For instance, the default type in '>]]>' is + integer, not float.

+

The default Size depends on the type. For integer it is + 8. For float it is 64. For binary it is all of the binary. In + matching, this default value is only valid for the very last + element. All other binary elements in matching must have a size + specification.

+

The default unit depends on the the type. For integer, + float, and bitstring it is 1. For binary it is 8.

+

The default signedness is unsigned.

+

The default endianness is big.

+
+ +
+ Constructing Binaries and Bitstrings +

This section describes the rules for constructing binaries using + the bit syntax. Unlike when constructing lists or tuples, + the construction of a binary can fail with a badarg + exception.

+

There can be zero or more segments in a binary to be + constructed. The expression '>]]>' constructs a zero + length binary.

+

Each segment in a binary can consist of zero or more bits. + There are no alignment rules for individual segments of type + integer and float. For binaries and bitstrings + without size, the unit specifies the alignment. Since the default + alignment for the binary type is 8, the size of a binary + segment must be a multiple of 8 bits (i.e. only whole bytes). + Example:

+ >]]> +

The variable Bin must contain a whole number of bytes, + because the binary type defaults to unit:8. + A badarg exception will be generated if Bin would + consist of (for instance) 17 bits.

+ +

On the other hand, the variable Bitstring may consist of + any number of bits, for instance 0, 1, 8, 11, 17, 42, and so on, + because the default unit for bitstrings is 1.

+ +

For clarity, it is recommended not to change the unit + size for binaries, but to use binary when you need byte + alignment, and bitstring when you need bit alignment.

 + +

The following example

+ >]]> +

will successfully construct a bitstring of 7 bits. + (Provided that all of X and Y are integers.)

+

As noted earlier, segments have the following general syntax:

+

Value:Size/TypeSpecifierList

+

When constructing binaries, Value and Size can be + any Erlang expression. However, for syntactical reasons, both + Value and Size must be enclosed in parenthesis if + the expression consists of anything more than a single literal + or variable. The following gives a compiler syntax error:

+ >]]> +

This expression must be rewritten to

+ >]]> +

in order to be accepted by the compiler.

+ +
+ Including Literal Strings +

As syntactic sugar, an literal string may be written instead + of a element.

+ >]]> +

which is syntactic sugar for

+ >]]> +
+
+ +
+ Matching Binaries +

This section describes the rules for matching binaries using + the bit syntax.

+

There can be zero or more segments in a binary pattern. + A binary pattern can occur in every place patterns are allowed, + also inside other patterns. Binary patterns cannot be nested.

+

The pattern '>]]>' matches a zero length binary.

+

Each segment in a binary can consist of zero or more bits.

+

A segment of type binary must have a size evenly + divisible by 8 (or divisible by the unit size, if the unit size has been changed).

+

A segment of type bitstring has no restrictions on the size.

+

As noted earlier, segments have the following general syntax:

+

Value:Size/TypeSpecifierList

+

When matching Value value must be either a variable or + an integer or floating point literal. Expressions are not + allowed.

+

Size must be an integer literal, or a previously bound + variable. Note that the following is not allowed:

+ >) -> + {X,T}.]]> +

The two occurrences of N are not related. The compiler + will complain that the N in the size field is unbound.

+

The correct way to write this example is like this:

+ + <> = Bin, + {X,T}.]]> + +
+ Getting the Rest of the Binary or Bitstring +

To match out the rest of a binary, specify a binary field + without size:

+ >) ->]]> +

The size of the tail must be evenly divisible by 8.

+ +

To match out the rest of a bitstring, specify a field + without size:

+ >) ->]]> +

There is no restriction on the number of bits in the tail.

+
+
+ +
+ Appending to a Binary +

In R12B, the following function for creating a binary out of + a list of triples of integers is now efficient:

+ + triples_to_bin(T, <<>>). + +triples_to_bin([{X,Y,Z} | T], Acc) -> + triples_to_bin(T, <>); % inefficient before R12B +triples_to_bin([], Acc) -> + Acc.]]> +

In previous releases, this function was highly inefficient, because + the binary constructed so far (Acc) was copied in each recursion step. + That is no longer the case. See the Efficiency Guide for more information.

+
+ + diff --git a/system/doc/programming_examples/book.xml b/system/doc/programming_examples/book.xml new file mode 100644 index 0000000000..91346ceea4 --- /dev/null +++ b/system/doc/programming_examples/book.xml @@ -0,0 +1,37 @@ + + + + +
+ + 20032009 + Ericsson AB. All Rights Reserved. + + + The contents of this file are subject to the Erlang Public License, + Version 1.1, (the "License"); you may not use this file except in + compliance with the License. You should have received a copy of the + Erlang Public License along with this software. If not, it can be + retrieved online at http://www.erlang.org/. + + Software distributed under the License is distributed on an "AS IS" + basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See + the License for the specific language governing rights and limitations + under the License. + + + + Programming Examples + + + + +
+ Programming Examples + + + + + + + diff --git a/system/doc/programming_examples/fun_test.erl b/system/doc/programming_examples/fun_test.erl new file mode 100644 index 0000000000..8472fd87f8 --- /dev/null +++ b/system/doc/programming_examples/fun_test.erl @@ -0,0 +1,17 @@ +%1 +-module(fun_test). +-export([t1/0, t2/0, t3/0, t4/0, double/1]). +-import(lists, [map/2]). + +t1() -> map(fun(X) -> 2 * X end, [1,2,3,4,5]). + +t2() -> map(fun double/1, [1,2,3,4,5]). + +t3() -> map({?MODULE, double}, [1,2,3,4,5]). + +double(X) -> X * 2. +%1 + + +t4() -> + "hello world". diff --git a/system/doc/programming_examples/funparse.erl b/system/doc/programming_examples/funparse.erl new file mode 100644 index 0000000000..5e23c90df9 --- /dev/null +++ b/system/doc/programming_examples/funparse.erl @@ -0,0 +1,74 @@ +-module(funparse). +-compile(export_all). +-import(lists, [reverse/1]). + +%17 +%% > hof:parse([a,c]). +%% {ok,{'and',{'or',1,{const,a}},{'or',1,{const,c}}}} +%% > hof:parse([a,d]). +%% {ok,{'and',{'or',1,{const,a}},{'or',2,{const,d}}}} +%% > hof:parse([b,c]). +%% {ok,{'and',{'or',2,{const,b}},{'or',1,{const,c}}}} +%% > hof:parse([b,d]). +%% {ok,{'and',{'or',2,{const,b}},{'or',2,{const,d}}}} +%% > hof:parse([a,b]). +%% fail +%17 + +%% Grammar = (a | b) & (c | d) + +%12 +parse(List) -> + (grammar())(List). +%12 + +%13 +grammar() -> + pand( + por(pconst(a), pconst(b)), + por(pconst(c), pconst(d))). +%13 + +%14 +pconst(X) -> + fun (T) -> + case T of + [X|T1] -> {ok, {const, X}, T1}; + _ -> fail + end + end. +%14 + +%15 +por(P1, P2) -> + fun (T) -> + case P1(T) of + {ok, R, T1} -> + {ok, {'or',1,R}, T1}; + fail -> + case P2(T) of + {ok, R1, T1} -> + {ok, {'or',2,R1}, T1}; + fail -> + fail + end + end + end. +%15 + +%16 +pand(P1, P2) -> + fun (T) -> + case P1(T) of + {ok, R1, T1} -> + case P2(T1) of + {ok, R2, T2} -> + {ok, {'and', R1, R2}}; + fail -> + fail + end; + fail -> + fail + end + end. +%16 diff --git a/system/doc/programming_examples/funs.xmlsrc b/system/doc/programming_examples/funs.xmlsrc new file mode 100644 index 0000000000..92f99cf6d3 --- /dev/null +++ b/system/doc/programming_examples/funs.xmlsrc @@ -0,0 +1,515 @@ + + + + +
+ + 20032009 + Ericsson AB. All Rights Reserved. + + + The contents of this file are subject to the Erlang Public License, + Version 1.1, (the "License"); you may not use this file except in + compliance with the License. You should have received a copy of the + Erlang Public License along with this software. If not, it can be + retrieved online at http://www.erlang.org/. + + Software distributed under the License is distributed on an "AS IS" + basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See + the License for the specific language governing rights and limitations + under the License. + + + + Funs + + + + + funs.xml +
+ +
+ Example 1 - map +

If we want to double every element in a list, we could write a + function named double:

+ +double([H|T]) -> [2*H|double(T)]; +double([]) -> []. +

This function obviously doubles the argument entered as input + as follows:

+ 
+> double([1,2,3,4]).
+[2,4,6,8]
+

We now add the function add_one, which adds one to every + element in a list:

+ +add_one([H|T]) -> [H+1|add_one(T)]; +add_one([]) -> []. +

These functions, double and add_one, have a very + similar structure. We can exploit this fact and write a function + map which expresses this similarity:

+ +

We can now express the functions double and + add_one in terms of map as follows:

+ +double(L) -> map(fun(X) -> 2*X end, L). +add_one(L) -> map(fun(X) -> 1 + X end, L). +

map(F, List) is a function which takes a function + F and a list L as arguments and returns the new + list which is obtained by applying F to each of + the elements in L.

+

The process of abstracting out the common features of a number + of different programs is called procedural abstraction. + Procedural abstraction can be used in order to write several + different functions which have a similar structure, but differ + only in some minor detail. This is done as follows:

+ + write one function which represents the common features of + these functions + parameterize the difference in terms of functions which + are passed as arguments to the common function. + +
+ +
+ Example 2 - foreach +

This example illustrates procedural abstraction. Initially, we + show the following two examples written as conventional + functions:

+ + all elements of a list are printed onto a stream + a message is broadcast to a list of processes. + + +print_list(Stream, [H|T]) -> + io:format(Stream, "~p~n", [H]), + print_list(Stream, T); +print_list(Stream, []) -> + true. + +broadcast(Msg, [Pid|Pids]) -> + Pid ! Msg, + broadcast(Msg, Pids); +broadcast(_, []) -> + true. +

Both these functions have a very similar structure. They both + iterate over a list doing something to each element in the list. + The "something" has to be carried round as an extra argument to + the function which does this.

+

The function foreach expresses this similarity:

+ +

Using foreach, print_list becomes:

+ +foreach(fun(H) -> io:format(S, "~p~n",[H]) end, L) +

broadcast becomes:

+ +foreach(fun(Pid) -> Pid ! M end, L) +

foreach is evaluated for its side-effect and not its + value. foreach(Fun ,L) calls Fun(X) for each + element X in L and the processing occurs in + the order in which the elements were defined in L. + map does not define the order in which its elements are + processed.

+
+ +
+ The Syntax of Funs +

Funs are written with the syntax:

+ +F = fun (Arg1, Arg2, ... ArgN) -> + ... + end +

This creates an anonymous function of N arguments and + binds it to the variable F.

+

If we have already written a function in the same module and + wish to pass this function as an argument, we can use + the following syntax:

+ +F = fun FunctionName/Arity +

With this form of function reference, the function which is + referred to does not need to be exported from the module.

+

We can also refer to a function defined in a different module + with the following syntax:

+ +F = {Module, FunctionName} +

In this case, the function must be exported from the module in + question.

+

The follow program illustrates the different ways of creating + funs:

+ +

We can evaluate the fun F with the syntax:

+ +F(Arg1, Arg2, ..., Argn) +

To check whether a term is a fun, use the test + is_function/1 in a guard. Example:

+ +f(F, Args) when is_function(F) -> + apply(F, Args); +f(N, _) when is_integer(N) -> + N. +

Funs are a distinct type. The BIFs erlang:fun_info/1,2 can + be used to retrieve information about a fun, and the BIF + erlang:fun_to_list/1 returns a textual representation of a fun. + The check_process_code/2 BIF returns true if the process + contains funs that depend on the old version of a module.

+ +

In OTP R5 and earlier releases, funs were represented using + tuples.

+ +
+ +
+ Variable Bindings Within a Fun +

The scope rules for variables which occur in funs are as + follows:

+ + All variables which occur in the head of a fun are assumed + to be "fresh" variables. + Variables which are defined before the fun, and which + occur in function calls or guard tests within the fun, have + the values they had outside the fun. + No variables may be exported from a fun. + +

The following examples illustrate these rules:

+ +print_list(File, List) -> + {ok, Stream} = file:open(File, write), + foreach(fun(X) -> io:format(Stream,"~p~n",[X]) end, List), + file:close(Stream). +

In the above example, the variable X which is defined in + the head of the fun is a new variable. The value of the variable + Stream which is used within within the fun gets its value + from the file:open line.

+

Since any variable which occurs in the head of a fun is + considered a new variable it would be equally valid to write:

+ +print_list(File, List) -> + {ok, Stream} = file:open(File, write), + foreach(fun(File) -> + io:format(Stream,"~p~n",[File]) + end, List), + file:close(Stream). +

In this example, File is used as the new variable + instead of X. This is rather silly since code in the body + of the fun cannot refer to the variable File which is + defined outside the fun. Compiling this example will yield + the diagnostic:

+ +./FileName.erl:Line: Warning: variable 'File' + shadowed in 'lambda head' +

This reminds us that the variable File which is defined + inside the fun collides with the variable File which is + defined outside the fun.

+

The rules for importing variables into a fun has the consequence + that certain pattern matching operations have to be moved into + guard expressions and cannot be written in the head of the fun. + For example, we might write the following code if we intend + the first clause of F to be evaluated when the value of + its argument is Y:

+ +f(...) -> + Y = ... + map(fun(X) when X == Y -> + ; + (_) -> + ... + end, ...) + ... +

instead of

+ +f(...) -> + Y = ... + map(fun(Y) -> + ; + (_) -> + ... + end, ...) + ... +
+ +
+ Funs and the Module Lists +

The following examples show a dialogue with the Erlang shell. + All the higher order functions discussed are exported from + the module lists.

+ +
+ map + +

map takes a function of one argument and a list of + terms. It returns the list obtained by applying the function + to every argument in the list.

+ 
+> Double = fun(X) -> 2 * X end.
+#Fun<erl_eval.6.72228031>
+> lists:map(Double, [1,2,3,4,5]).
+[2,4,6,8,10]
+

When a new fun is defined in the shell, the value of the Fun + is printed as ]]>.

+
+ +
+ any + +

any takes a predicate P of one argument and a + list of terms. A predicate is a function which returns + true or false. any is true if there is a + term X in the list such that P(X) is true.

+

We define a predicate Big(X) which is true if + its argument is greater that 10.

+ 
+> Big =  fun(X) -> if X > 10 -> true; true -> false end end.
+#Fun<erl_eval.6.72228031>
+> lists:any(Big, [1,2,3,4]).
+false
+> lists:any(Big, [1,2,3,12,5]).
+true
+
+ +
+ all + +

all has the same arguments as any. It is true + if the predicate applied to all elements in the list is true.

+ 
+> lists:all(Big, [1,2,3,4,12,6]).   
+false
+> lists:all(Big, [12,13,14,15]).       
+true
+
+ +
+ foreach + +

foreach takes a function of one argument and a list of + terms. The function is applied to each argument in the list. + foreach returns ok. It is used for its + side-effect only.

+ 
+> lists:foreach(fun(X) -> io:format("~w~n",[X]) end, [1,2,3,4]). 
+1
+2
+3
+4
+ok
+
+ +
+ foldl + +

foldl takes a function of two arguments, an + accumulator and a list. The function is called with two + arguments. The first argument is the successive elements in + the list, the second argument is the accumulator. The function + must return a new accumulator which is used the next time + the function is called.

+

If we have a list of lists L = ["I","like","Erlang"], + then we can sum the lengths of all the strings in L as + follows:

+ 
+> L = ["I","like","Erlang"].
+["I","like","Erlang"]
+10> lists:foldl(fun(X, Sum) -> length(X) + Sum end, 0, L).                    
+11
+

foldl works like a while loop in an imperative + language:

+ +L = ["I","like","Erlang"], +Sum = 0, +while( L != []){ + Sum += length(head(L)), + L = tail(L) +end +
+ +
+ mapfoldl + +

mapfoldl simultaneously maps and folds over a list. + The following example shows how to change all letters in + L to upper case and count them.

+

First upcase:

+ 
+> Upcase =  fun(X) when $a =< X,  X =< $z -> X + $A - $a;
+(X) -> X 
+end.
+#Fun<erl_eval.6.72228031>
+> Upcase_word = 
+fun(X) -> 
+lists:map(Upcase, X) 
+end.
+#Fun<erl_eval.6.72228031>
+> Upcase_word("Erlang").
+"ERLANG"
+> lists:map(Upcase_word, L).
+["I","LIKE","ERLANG"]
+

Now we can do the fold and the map at the same time:

+ 
+> lists:mapfoldl(fun(Word, Sum) ->
+{Upcase_word(Word), Sum + length(Word)}
+end, 0, L).
+{["I","LIKE","ERLANG"],11}
+
+ +
+ filter + +

filter takes a predicate of one argument and a list + and returns all element in the list which satisfy + the predicate.

+ 
+> lists:filter(Big, [500,12,2,45,6,7]).
+[500,12,45]
+

When we combine maps and filters we can write very succinct + code. For example, suppose we want to define a set difference + function. We want to define diff(L1, L2) to be + the difference between the lists L1 and L2. + This is the list of all elements in L1 which are not contained + in L2. This code can be written as follows:

+ +diff(L1, L2) -> + filter(fun(X) -> not member(X, L2) end, L1). +

The AND intersection of the list L1 and L2 is + also easily defined:

+ +intersection(L1,L2) -> filter(fun(X) -> member(X,L1) end, L2). +
+ +
+ takewhile + +

takewhile(P, L) takes elements X from a list + L as long as the predicate P(X) is true.

+ 
+> lists:takewhile(Big, [200,500,45,5,3,45,6]).  
+[200,500,45]
+
+ +
+ dropwhile + +

dropwhile is the complement of takewhile.

+ 
+> lists:dropwhile(Big, [200,500,45,5,3,45,6]).
+[5,3,45,6]
+
+ +
+ splitwith + +

splitwith(P, L) splits the list L into the two + sub-lists {L1, L2}, where L = takewhile(P, L) + and L2 = dropwhile(P, L).

+ 
+> lists:splitwith(Big, [200,500,45,5,3,45,6]).
+{[200,500,45],[5,3,45,6]}
+
+
+ +
+ Funs Which Return Funs +

So far, this section has only described functions which take + funs as arguments. It is also possible to write more powerful + functions which themselves return funs. The following examples + illustrate these type of functions.

+ +
+ Simple Higher Order Functions +

Adder(X) is a function which, given X, returns + a new function G such that G(K) returns + K + X.

+ 
+> Adder = fun(X) -> fun(Y) -> X + Y end end.
+#Fun<erl_eval.6.72228031>
+> Add6 = Adder(6).
+#Fun<erl_eval.6.72228031>
+> Add6(10).
+16
+
+ +
+ Infinite Lists +

The idea is to write something like:

+ +-module(lazy). +-export([ints_from/1]). +ints_from(N) -> + fun() -> + [N|ints_from(N+1)] + end. +

Then we can proceed as follows:

+ 
+> XX = lazy:ints_from(1).
+#Fun<lazy.0.29874839>
+> XX().
+[1|#Fun<lazy.0.29874839>]
+> hd(XX()).
+1
+> Y = tl(XX()).
+#Fun<lazy.0.29874839>
+> hd(Y()).
+2
+

etc. - this is an example of "lazy embedding".

+
+ +
+ Parsing +

The following examples show parsers of the following type:

+ 
+Parser(Toks) -> {ok, Tree, Toks1} | fail
+

Toks is the list of tokens to be parsed. A successful + parse returns {ok, Tree, Toks1}, where Tree is a + parse tree and Toks1 is a tail of Tree which + contains symbols encountered after the structure which was + correctly parsed. Otherwise fail is returned.

+

The example which follows illustrates a simple, functional + parser which parses the grammar:

+ 
+(a | b) & (c | d)
+

The following code defines a function pconst(X) in + the module funparse, which returns a fun which parses a + list of tokens.

+ +

This function can be used as follows:

+ 
+> P1 = funparse:pconst(a).
+#Fun<funparse.0.22674075>
+> P1([a,b,c]).
+{ok,{const,a},[b,c]}
+> P1([x,y,z]).     
+fail
+

Next, we define the two higher order functions pand + and por which combine primitive parsers to produce more + complex parsers. Firstly pand:

+ +

Given a parser P1 for grammar G1, and a parser + P2 for grammar G2, pand(P1, P2) returns a + parser for the grammar which consists of sequences of tokens + which satisfy G1 followed by sequences of tokens which + satisfy G2.

+

por(P1, P2) returns a parser for the language + described by the grammar G1 or G2.

+ +

The original problem was to parse the grammar + . The following code addresses this + problem:

+ +

The following code adds a parser interface to the grammar:

+ +

We can test this parser as follows:

+ 
+> funparse:parse([a,c]).
+{ok,{'and',{'or',1,{const,a}},{'or',1,{const,c}}}}
+> funparse:parse([a,d]). 
+{ok,{'and',{'or',1,{const,a}},{'or',2,{const,d}}}}
+> funparse:parse([b,c]).   
+{ok,{'and',{'or',2,{const,b}},{'or',1,{const,c}}}}
+> funparse:parse([b,d]). 
+{ok,{'and',{'or',2,{const,b}},{'or',2,{const,d}}}}
+> funparse:parse([a,b]).   
+fail
+
+
+ + diff --git a/system/doc/programming_examples/funs1.erl b/system/doc/programming_examples/funs1.erl new file mode 100644 index 0000000000..8cf20378ea --- /dev/null +++ b/system/doc/programming_examples/funs1.erl @@ -0,0 +1,125 @@ +-module(funs1). +-compile(export_all). +-import(lists, [reverse/1]). + +%1 +map(F, [H|T]) -> [F(H)|map(F, T)]; +map(F, []) -> []. +%1 + +%2 +foreach(F, [H|T]) -> + F(H), + foreach(F, T); +foreach(F, []) -> + ok. +%2 +% +%3 +all(Pred, [H|T]) -> + case Pred(H) of + true -> all(Pred, T); + false -> false + end; +all(Pred, []) -> + true. +%3 +%4 +any(Pred, [H|T]) -> + case Pred(H) of + true -> true; + false -> any(Pred, T) + end; +any(Pred, []) -> + false. +%4 +%5 +takewhile(Pred, [H|T]) -> + case Pred(H) of + true -> [H|takewhile(Pred, T)]; + false -> [] + end; +takewhile(Pred, []) -> + []. +%5 +%6 +dropwhile(Pred, [H|T]) -> + case Pred(H) of + true -> dropwhile(Pred, T); + false -> [H|T] + end; +dropwhile(Pred, []) -> + []. +%6 +%7 +splitwith(Pred, L) -> + splitwith(Pred, L, []). + +splitwith(Pred, [H|T], L) -> + case Pred(H) of + true -> splitwith(Pred, T, [H|L]); + false -> {reverse(L), [H|T]} + end; +splitwith(Pred, [], L) -> + {reverse(L), []}. +%7 + +flatmap(F, [Hd|Tail]) -> + F(Hd) ++ flatmap(F, Tail); +flatmap(F, []) -> []. + +%8 +foldl(F, Accu, [Hd|Tail]) -> + foldl(F, F(Hd, Accu), Tail); +foldl(F, Accu, []) -> Accu. +%8 +% +foldr(F, Accu, [Hd|Tail]) -> + F(Hd, foldr(F, Accu, Tail)); +foldr(F, Accu, []) -> Accu. +%9 +filter(F, [H|T]) -> + case F(H) of + true -> [H|filter(F, T)]; + false -> filter(F, T) + end; +filter(F, []) -> []. +%9 +%10 +mapfoldl(F, Accu0, [Hd|Tail]) -> + {R,Accu1} = F(Hd, Accu0), + {Rs,Accu2} = mapfoldl(F, Accu1, Tail), + {[R|Rs], Accu2}; +mapfoldl(F, Accu, []) -> {[], Accu}. +%10 +mapfoldr(F, Accu0, [Hd|Tail]) -> + {Rs,Accu1} = mapfoldr(F, Accu0, Tail), + {R,Accu2} = F(Hd, Accu1), + {[R|Rs],Accu2}; +mapfoldr(F, Accu, []) -> {[], Accu}. +%11 +first(Pred, [H|T]) -> + case Pred(H) of + true -> + {true, H}; + false -> + first(Pred, T) + end; +first(Pred, []) -> + false. +%11 +% +compose(F, G) -> + fun(X) -> + F(G(X)) + end. + +%20 +iterate(N, F) -> + iterate(N, N+1, F). + +iterate(Stop, Stop, _) -> + []; +iterate(N, Stop, Fun) -> + [Fun(N)|iterate(N+1, Stop, Fun)]. +%20 diff --git a/system/doc/programming_examples/list_comprehensions.xml b/system/doc/programming_examples/list_comprehensions.xml new file mode 100644 index 0000000000..825459238b --- /dev/null +++ b/system/doc/programming_examples/list_comprehensions.xml @@ -0,0 +1,206 @@ + + + + +
+ + 20032009 + Ericsson AB. All Rights Reserved. + + + The contents of this file are subject to the Erlang Public License, + Version 1.1, (the "License"); you may not use this file except in + compliance with the License. You should have received a copy of the + Erlang Public License along with this software. If not, it can be + retrieved online at http://www.erlang.org/. + + Software distributed under the License is distributed on an "AS IS" + basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See + the License for the specific language governing rights and limitations + under the License. + + + + List Comprehensions + + + + + list_comprehensions.xml +
+ +
+ Simple Examples +

We start with a simple example:

+ 
+> [X || X <- [1,2,a,3,4,b,5,6], X > 3].
+[a,4,b,5,6]
+

This should be read as follows:

+ +

The list of X such that X is taken from the list + [1,2,a,...] and X is greater than 3.

+ +

The notation is a generator and + the expression X > 3 is a filter.

+

An additional filter can be added in order to restrict + the result to integers:

+ 
+> [X || X <- [1,2,a,3,4,b,5,6], integer(X), X > 3].
+[4,5,6]
+

Generators can be combined. For example, the Cartesian product + of two lists can be written as follows:

+ 
+> [{X, Y} || X <- [1,2,3], Y <- [a,b]].
+[{1,a},{1,b},{2,a},{2,b},{3,a},{3,b}]
+
+ +
+ Quick Sort +

The well known quick sort routine can be written as follows:

+ + sort([ X || X <- T, X < Pivot]) ++ + [Pivot] ++ + sort([ X || X <- T, X >= Pivot]); +sort([]) -> [].]]> +

The expression is the list of + all elements in T, which are less than Pivot.

+

= Pivot]]]> is the list of all elements in + T, which are greater or equal to Pivot.

+

To sort a list, we isolate the first element in the list and + split the list into two sub-lists. The first sub-list contains + all elements which are smaller than the first element in + the list, the second contains all elements which are greater + than or equal to the first element in the list. We then sort + the sub-lists and combine the results.

+
+ +
+ Permutations +

The following example generates all permutations of + the elements in a list:

+ [[]]; +perms(L) -> [[H|T] || H <- L, T <- perms(L--[H])].]]> +

We take take H from L in all possible ways. + The result is the set of all lists [H|T], where T + is the set of all possible permutations of L with + H removed.

+ 
+> perms([b,u,g]).
+[[b,u,g],[b,g,u],[u,b,g],[u,g,b],[g,b,u],[g,u,b]]
+
+ +
+ Pythagorean Triplets +

Pythagorean triplets are sets of integers {A,B,C} such + that A**2 + B**2 = C**2.

+

The function pyth(N) generates a list of all integers + {A,B,C} such that A**2 + B**2 = C**2 and where + the sum of the sides is equal to or less than N.

+ + [ {A,B,C} || + A <- lists:seq(1,N), + B <- lists:seq(1,N), + C <- lists:seq(1,N), + A+B+C =< N, + A*A+B*B == C*C + ].]]> + 
+> pyth(3).
+[].
+> pyth(11).
+[].
+> pyth(12).
+[{3,4,5},{4,3,5}]
+> pyth(50).
+[{3,4,5},
+ {4,3,5},
+ {5,12,13},
+ {6,8,10},
+ {8,6,10},
+ {8,15,17},
+ {9,12,15},
+ {12,5,13},
+ {12,9,15},
+ {12,16,20},
+ {15,8,17},
+ {16,12,20}]
+

The following code reduces the search space and is more + efficient:

+ + [{A,B,C} || + A <- lists:seq(1,N-2), + B <- lists:seq(A+1,N-1), + C <- lists:seq(B+1,N), + A+B+C =< N, + A*A+B*B == C*C ].]]> +
+ +
+ Simplifications with List Comprehensions +

As an example, list comprehensions can be used to simplify some + of the functions in lists.erl:

+ [X || L1 <- L, X <- L1]. +map(Fun, L) -> [Fun(X) || X <- L]. +filter(Pred, L) -> [X || X <- L, Pred(X)].]]> +
+ +
+ Variable Bindings in List Comprehensions +

The scope rules for variables which occur in list + comprehensions are as follows:

+ + all variables which occur in a generator pattern are + assumed to be "fresh" variables + any variables which are defined before the list + comprehension and which are used in filters have the values + they had before the list comprehension + no variables may be exported from a list comprehension. + +

As an example of these rules, suppose we want to write + the function select, which selects certain elements from + a list of tuples. We might write + [Y || {X, Y} <- L].]]> with the intention + of extracting all tuples from L where the first item is + X.

+

Compiling this yields the following diagnostic:

+ +./FileName.erl:Line: Warning: variable 'X' shadowed in generate +

This diagnostic warns us that the variable X in + the pattern is not the same variable as the variable X + which occurs in the function head.

+

Evaluating select yields the following result:

+ 
+> select(b,[{a,1},{b,2},{c,3},{b,7}]).
+[1,2,3,7]
+

This result is not what we wanted. To achieve the desired + effect we must write select as follows:

+ [Y || {X1, Y} <- L, X == X1].]]> +

The generator now contains unbound variables and the test has + been moved into the filter. This now works as expected:

+ 
+> select(b,[{a,1},{b,2},{c,3},{b,7}]).
+[2,7]
+

One consequence of the rules for importing variables into a + list comprehensions is that certain pattern matching operations + have to be moved into the filters and cannot be written directly + in the generators. To illustrate this, do not write as follows:

+ + Y = ... + [ Expression || PatternInvolving Y <- Expr, ...] + ...]]> +

Instead, write as follows:

+ + Y = ... + [ Expression || PatternInvolving Y1 <- Expr, Y == Y1, ...] + ...]]> +
+ + diff --git a/system/doc/programming_examples/make.dep b/system/doc/programming_examples/make.dep new file mode 100644 index 0000000000..b0655f56b3 --- /dev/null +++ b/system/doc/programming_examples/make.dep @@ -0,0 +1,20 @@ +# ---------------------------------------------------- +# >>>> Do not edit this file <<<< +# This file was automaticly generated by +# /home/otp/bin/docdepend +# ---------------------------------------------------- + + +# ---------------------------------------------------- +# TeX files that the DVI file depend on +# ---------------------------------------------------- + +book.dvi: bit_syntax.tex book.tex funs.tex list_comprehensions.tex \ + part.tex records.tex + +# ---------------------------------------------------- +# Source inlined when transforming from source to LaTeX +# ---------------------------------------------------- + +funs.tex: fun_test.erl funparse.erl funs1.erl + diff --git a/system/doc/programming_examples/part.xml b/system/doc/programming_examples/part.xml new file mode 100644 index 0000000000..5b22ddf82f --- /dev/null +++ b/system/doc/programming_examples/part.xml @@ -0,0 +1,39 @@ + + + + +
+ + 20032009 + Ericsson AB. All Rights Reserved. + + + The contents of this file are subject to the Erlang Public License, + Version 1.1, (the "License"); you may not use this file except in + compliance with the License. You should have received a copy of the + Erlang Public License along with this software. If not, it can be + retrieved online at http://www.erlang.org/. + + Software distributed under the License is distributed on an "AS IS" + basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See + the License for the specific language governing rights and limitations + under the License. + + + + Programming Examples + + + + +
+ +

This chapter contains examples on using records, funs, list + comprehensions and the bit syntax.

+ + + + + + + diff --git a/system/doc/programming_examples/records.xml b/system/doc/programming_examples/records.xml new file mode 100644 index 0000000000..2f2434f11c --- /dev/null +++ b/system/doc/programming_examples/records.xml @@ -0,0 +1,232 @@ + + + + +
+ + 20032009 + Ericsson AB. All Rights Reserved. + + + The contents of this file are subject to the Erlang Public License, + Version 1.1, (the "License"); you may not use this file except in + compliance with the License. You should have received a copy of the + Erlang Public License along with this software. If not, it can be + retrieved online at http://www.erlang.org/. + + Software distributed under the License is distributed on an "AS IS" + basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See + the License for the specific language governing rights and limitations + under the License. + + + + Records + + + + + records.xml +
+ +
+ Records vs Tuples +

The main advantage of using records instead of tuples is that + fields in a record are accessed by name, whereas fields in a + tuple are accessed by position. To illustrate these differences, + suppose that we want to represent a person with the tuple + {Name, Address, Phone}.

+

We must remember that the Name field is the first + element of the tuple, the Address field is the second + element, and so on, in order to write functions which manipulate + this data. For example, to extract data from a variable P + which contains such a tuple we might write the following code + and then use pattern matching to extract the relevant fields.

+ +Name = element(1, P), +Address = element(2, P), +... +

Code like this is difficult to read and understand and errors + occur if we get the numbering of the elements in the tuple wrong. + If we change the data representation by re-ordering the fields, + or by adding or removing a field, then all references to + the person tuple, wherever they occur, must be checked and + possibly modified.

+

Records allow us to refer to the fields by name and not + position. We use a record instead of a tuple to store the data. + If we write a record definition of the type shown below, we can + then refer to the fields of the record by name.

+ +-record(person, {name, phone, address}). +

For example, if P is now a variable whose value is a + person record, we can code as follows in order to access + the name and address fields of the records.

+ +Name = P#person.name, +Address = P#person.address, +... +

Internally, records are represented using tagged tuples:

+ +{person, Name, Phone, Address} +
+ +
+ Defining a Record +

This definition of a person will be used in many of + the examples which follow. It contains three fields, name, + phone and address. The default values for + name and phone is "" and [], respectively. + The default value for address is the atom + undefined, since no default value is supplied for this + field:

+ 
+-record(person, {name = "", phone = [], address}).
+

We have to define the record in the shell in order to be able + use the record syntax in the examples:

+ 
+> rd(person, {name = "", phone = [], address}).
+person
+

This is due to the fact that record definitions are available + at compile time only, not at runtime. See shell(3) for + details on records in the shell. +

+
+ +
+ Creating a Record +

A new person record is created as follows:

+ 
+> #person{phone=[0,8,2,3,4,3,1,2], name="Robert"}.
+#person{name = "Robert",phone = [0,8,2,3,4,3,1,2],address = undefined}
+

Since the address field was omitted, its default value + is used.

+

There is a new feature introduced in Erlang 5.1/OTP R8B, + with which you can set a value to all fields in a record, + overriding the defaults in the record specification. The special + field _, means "all fields not explicitly specified".

+ 
+> #person{name = "Jakob", _ = '_'}.
+#person{name = "Jakob",phone = '_',address = '_'}
+

It is primarily intended to be used in ets:match/2 and + mnesia:match_object/3, to set record fields to the atom + '_'. (This is a wildcard in ets:match/2.)

+
+ +
+ Accessing a Record Field + 
+> P = #person{name = "Joe", phone = [0,8,2,3,4,3,1,2]}.
+#person{name = "Joe",phone = [0,8,2,3,4,3,1,2],address = undefined}
+> P#person.name.
+"Joe"
+
+ +
+ Updating a Record + 
+> P1 = #person{name="Joe", phone=[1,2,3], address="A street"}.
+#person{name = "Joe",phone = [1,2,3],address = "A street"}
+> P2 = P1#person{name="Robert"}.
+#person{name = "Robert",phone = [1,2,3],address = "A street"}
+
+ +
+ Type Testing +

The following example shows that the guard succeeds if + P is record of type person.

+ 
+foo(P) when is_record(P, person) -> a_person;
+foo(_) -> not_a_person.
+
+ +
+ Pattern Matching +

Matching can be used in combination with records as shown in + the following example:

+ 
+> P3 = #person{name="Joe", phone=[0,0,7], address="A street"}.
+#person{name = "Joe",phone = [0,0,7],address = "A street"}
+> #person{name = Name} = P3, Name.
+"Joe"
+

The following function takes a list of person records + and searches for the phone number of a person with a particular + name:

+ +find_phone([#person{name=Name, phone=Phone} | _], Name) -> + {found, Phone}; +find_phone([_| T], Name) -> + find_phone(T, Name); +find_phone([], Name) -> + not_found. +

The fields referred to in the pattern can be given in any order.

+
+ +
+ Nested Records +

The value of a field in a record might be an instance of a + record. Retrieval of nested data can be done stepwise, or in a + single step, as shown in the following example:

+ 
+-record(name, {first = "Robert", last = "Ericsson"}).
+-record(person, {name = #name{}, phone}).
+
+demo() ->
+  P = #person{name= #name{first="Robert",last="Virding"}, phone=123},
+  First = (P#person.name)#name.first.
+

In this example, demo() evaluates to "Robert".

+
+ +
+ Example + 
+%% File: person.hrl
+
+%%-----------------------------------------------------------
+%% Data Type: person
+%% where:
+%%    name:  A string (default is undefined).
+%%    age:   An integer (default is undefined).
+%%    phone: A list of integers (default is []).
+%%    dict:  A dictionary containing various information 
+%%           about the person. 
+%%           A {Key, Value} list (default is the empty list).
+%%------------------------------------------------------------
+-record(person, {name, age, phone = [], dict = []}).
+ 
+-module(person).
+-include("person.hrl").
+-compile(export_all). % For test purposes only.
+
+%% This creates an instance of a person.
+%%   Note: The phone number is not supplied so the
+%%         default value [] will be used.
+
+make_hacker_without_phone(Name, Age) ->
+   #person{name = Name, age = Age, 
+           dict = [{computer_knowledge, excellent}, 
+                   {drinks, coke}]}.
+
+%% This demonstrates matching in arguments
+
+print(#person{name = Name, age = Age,
+              phone = Phone, dict = Dict}) ->
+  io:format("Name: ~s, Age: ~w, Phone: ~w ~n" 
+            "Dictionary: ~w.~n", [Name, Age, Phone, Dict]).
+
+%% Demonstrates type testing, selector, updating.
+
+birthday(P) when record(P, person) -> 
+   P#person{age = P#person.age + 1}.
+
+register_two_hackers() ->
+   Hacker1 = make_hacker_without_phone("Joe", 29),
+   OldHacker = birthday(Hacker1),
+   % The central_register_server should have 
+   % an interface function for this.
+   central_register_server ! {register_person, Hacker1},
+   central_register_server ! {register_person, 
+             OldHacker#person{name = "Robert", 
+                              phone = [0,8,3,2,4,5,3,1]}}.
+
+ + diff --git a/system/doc/programming_examples/xmlfiles.mk b/system/doc/programming_examples/xmlfiles.mk new file mode 100644 index 0000000000..5eb42a2881 --- /dev/null +++ b/system/doc/programming_examples/xmlfiles.mk @@ -0,0 +1,23 @@ +# +# %CopyrightBegin% +# +# Copyright Ericsson AB 2009. All Rights Reserved. +# +# The contents of this file are subject to the Erlang Public License, +# Version 1.1, (the "License"); you may not use this file except in +# compliance with the License. You should have received a copy of the +# Erlang Public License along with this software. If not, it can be +# retrieved online at http://www.erlang.org/. +# +# Software distributed under the License is distributed on an "AS IS" +# basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See +# the License for the specific language governing rights and limitations +# under the License. +# +# %CopyrightEnd% +# +PROG_EX_CHAPTER_FILES = \ + bit_syntax.xml \ + funs.xml \ + list_comprehensions.xml \ + records.xml -- cgit v1.2.3