Data structures

• Literals
  • atoms: foo, bar…
  • numbers: 123, 1.23…
  • bool: true, false
• Compound structures
  • tuples: {foo, 12, {bar, zot}}
  • listis: [], [1, 2, foo, bar]

Variables

• lexically scoped
• implicit scoping - the procedure definition
• untyped - assigned a value when introduced
• syntax: X, Foo, BarZot, _anything

No circular structures

circular data structures: the last element is a pointer to the first.

Concurrency

Concurrency is explicitly controlled by creation (spawning) of processes. A process is when created, given a function to evaluate. no one cares about the result. Sending and receiving messages is the only way to communicate with a process. no shared state

Registration

A node registers associate names to process identifiers.

register(alarm_process, Pid)

Knowing the registered name of a process you can look-up the process identifier.

The register is a shared data structure!

Node

Erlang nodes (an Erlang virtual machine) can be connected in a group . Each node has a unique name. Processes in one node can send messages to and receive messages from processes in other nodes using the same language constructs.

Failure detection

• a process can monitor another process
• if the process dies a messages is placed in the message queue
• the message will indicate if the termination was normal or abnormal or ….. if the communication was lost

Atomic termination

• A process can link to another process, if the process dies with an exception the linked process will die with the same exception.
• Processes that depend on each other are often linked together, if one dies they all die.