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Context:
Epsilon User's Manual and Reference
   . . .
   Introduction to EEL
      Epsilon Extension Language Features
      EEL Tutorial
   Epsilon Extension Language
      . . .
      Lexical Rules
      Scope of Variables
      Data Types
         Declarations
         Simple Declarators
         Pointer Declarators
         . . .
         Type Names
      Initialization
      Statements
      . . .
   Primitives and EEL Subroutines
      Buffer Primitives
      Display Primitives
      File Primitives
      . . .
      Defining Language Modes
   . . .

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Epsilon User's Manual and Reference > Epsilon Extension Language >

Data Types

EEL supports a rich set of data types. First there are the basic types:
int
These are 32 bit signed quantities. These correspond to integers. The value of an int ranges from -2,147,483,648 to 2,147,483,647.

short
These are like ints, except they are only 16 bits. Thus the value ranges from -32768 to 32767.

char
These are 16 bit unsigned quantities. They correspond to characters. For example, the buffer primitive curchar( ) returns an object of type char. The values range from 0 to 65535.

byte
These are 8 bit unsigned quantities.

spot
These are references to buffer positions. A spot can remember a buffer position in such a way that after inserting or deleting characters in the buffer, the spot will still be between the same two characters. Like pointers, spots can also hold the special value zero. See Spots.

Besides basic types, there is an infinite set of types derived from these. They are defined recursively as follows:

pointer
If t is some type, then pointer to t is also a type. Conceptually, this is the address of some object of type t. When you dereference an object of type pointer to t, the result is of type t.

array
If t is some type, then array of t is also a type.

structure
If t1, ... , tn are types, then structure of t1, ... , tn is also a type. Conceptually, a structure is a sequence of objects, where the jth object is of type tj.

union
If t1, ... , tn are types, then union of t1, ... , tn is also a type. Conceptually, a union is an object that can be of any of type t1, ... , tn at different times.

function
If t is a type, then function returning t is also a type.

Any function has a type, which is the type of the value it returns. If the function returns no value, it is of int type, but it is illegal to attempt to use the function's value.

Regardless of its type, you may declare any function to be a command (using the command keyword) if it takes no parameters. Commands like named-command on Alt-X will then complete on its name, but there is no other difference between commands and subroutines (user-defined functions which are not commands). Functions that the user is expected to invoke directly (by pressing a key, for example) are generally commands, while functions that act as helpers to commands are generally subroutines. Nothing prevents an EEL function from calling a command directly, though, and the user can invoke any subroutine directly as well (providing that it takes no arguments). Though a command may not have arguments, it may return a value (which is ignored when the user directly invokes it).



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