book

Introducing Erlang

by Simon St. Laurent

January 2013

Beginner to intermediate

204 pages

4h 26m

English

O'Reilly Media, Inc.

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Who This Book Is ForWho This Book Is Not ForWhat This Book Will Do For YouHow This Book WorksWhy I Wrote This BookOther ResourcesEtudes for ErlangAre You Sure You Want Erlang?Erlang Will Change YouConventions Used in This BookA Note on Erlang SyntaxUsing Code ExamplesHelp This Book GrowPlease Use It For GoodSafari® Books OnlineHow to Contact UsContent UpdatesApril 2, 2013Acknowledgments
InstallationFiring It UpFirst Steps: The ShellMoving through TextMoving through HistoryMoving through FilesDoing SomethingCalling FunctionsNumbers in ErlangWorking with Variables in the ShellSeeing Your Bound VariablesClearing Bound Variables in the Shell
Fun with funDefining ModulesFrom Module to FunFunctions and Variable ScopeModule DirectivesDocumenting CodeDocumenting ModulesDocumenting FunctionsDocumenting Your Application
AtomsPattern Matching with AtomsAtomic BooleansGuardsUnderscoring That You Don’t CareAdding Structure: TuplesPattern Matching with TuplesProcessing Tuples
Logic Inside of FunctionsEvaluating CasesIf This, Then ThatVariable Assignment in case and if ConstructsThe Gentlest Side Effect: io:formatSimple RecursionCounting DownCounting UpRecursing with Return Values
StringsAsking Users for InformationGathering TermsGathering CharactersReading Lines of Text
List BasicsSplitting Lists into Heads and TailsProcessing List ContentCreating Lists with Heads and TailsMixing Lists and TuplesBuilding a List of Lists
Simple Higher-Order FunctionsCreating New Lists with Higher-Order FunctionsReporting on a ListRunning List Values Through a FunctionFiltering List ValuesBeyond List ComprehensionsTesting ListsSplitting ListsFolding Lists
The Shell Is a ProcessSpawning Processes from ModulesLightweight ProcessesRegistering a ProcessWhen Processes BreakProcesses Talking Amongst ThemselvesWatching Your ProcessesBreaking Things and Linking Processes

Flavors of ErrorsCatching Runtime Errors as They HappenRaising Exceptions with throwLogging Progress and FailureDebugging through a GUITracing MessagesWatching Function Calls
From Tuples to RecordsSetting Up RecordsCreating and Reading RecordsUsing Records in Functions and ModulesStoring Records in Erlang Term StorageCreating and Populating a TableSimple QueriesA Key Feature: Overwriting ValuesETS Tables and ProcessesNext StepsStoring Records in MnesiaStarting up MnesiaCreating TablesReading DataQuery List Comprehensions
Creating Services with gen_serverA Simple SupervisorPackaging an Application
Moving Beyond the ShellDistributed ComputingProcessing Binary DataInput and OutputTesting, Analyzing, and RefactoringNetworking and the WebData StorageExtending ErlangLanguages Built on ErlangCommunitySharing the Gospel of Erlang
Shell CommandsReserved WordsOperatorsGuard ComponentsCommon FunctionsStrings and FormattingData Types for Documentation and Analysis

Content preview from Introducing Erlang

Appendix A. An Erlang Parts Catalog

Like every language, Erlang has drawers full of parts that are fun to peruse. These are a very few of the more common ones. If you want much much more, see http://www.erlang.org/doc/reference_manual/users_guide.html.

Shell Commands

You can use most Erlang functions from the shell, but these are ones that are exclusive to the shell.

Table A-1. Erlang shell commands

Command	Action
`q()`	Quits the shell and the Erlang runtime.
`c(file)`	Compiles the specified Erlang file.
`b()`	Displays all variable bindings.
`f()`	Clears all variable bindings.
`f(X)`	Clears specified variable binding.
`h()`	Prints the history list of commands.
`e(N)`	Repeats the command on line `N`.
`v(N)`	The return value of line `N`.
`catch_exception(boolean)`	Sets how strict the shell will be in passing errors.
`rd(Name,Definition)`	Defines a record type `Name` with contents specified by `Definition`.
`rr(File)`	Defines record types based on the contents of `File`.
`rf()`	Clears all record definitions. Can also clear specific definitions.
`rl()`	Lists all current record definitions.
`pwd()`	Gets the present working directory.
`ls()`	Lists files at the current location.
`cd(Directory)`	Changes to the specified `Directory`.

Reserved Words

There are a few Erlang terms you can’t use outside of their intended context.

The Erlang compiler will wonder what you’re trying to do if you use certain keywords as atoms or function names. It will try to treat your atoms as if they were code, and you can get very strange errors. After all, you should be able to have something ...