Lumesh Sys Module

Rust sys Module Documentation

Module Overview

Provides a core set of built-in functions related to environment variable operations for managing the runtime environment.

help sys

+-------------------------------------------------------------------------------------+
| KEY        VALUE                                                                    |
+=====================================================================================+
| has        Builtin@has        check if a variable is defined in current environment |
| env        Builtin@env        get root environment as a map                         |
| defined    Builtin@defined    check if a variable is defined in current environment |
|                               tree                                                  |
| set        Builtin@set        define a variable in root environment                 |
| err_codes  Builtin@err_codes  display runtime error codes                           |
| vars       Builtin@vars       get defined variables in current environment           |
| discard    Builtin@discard    send data to /dev/null                                |
| print_tty  Builtin@print_tty  print control sequence to tty                         |
| quote      Builtin@quote      quote an expression                                   |
| unset      Builtin@unset      undefine a variable in root environment               |
+-------------------------------------------------------------------------------------+

List of Environment Variable Related Functions

2. env

• Function: Get the list of variables in the top-level scope environment
• Parameters: None
• Return Value: A mapping structure of type Environment
• Example: (env) → Returns all bindings in the top-level scope

3. vars

• Function: Get the list of variables in the current environment
• Parameters: None
• Return Value: A hash table containing a mapping of (variable name → value)

4. set

• Function: Define/modify a variable in the top-level scope
• Parameters: (set name value)
  • name: A string type variable name
  • value: Any expression
• Return Value: Expression::None
• Error: Throws an exception if the number of parameters is not 2

5. unset

• Function: Remove the definition of a variable in the top-level scope
• Parameters: (unset name)
  • name: A string type variable name
• Return Value: Expression::None
• Error: Throws an exception if the number of parameters is not 1

6. defined

• Function: Check if a variable is defined in the current and parent scopes
• Parameters: (defined name)
  • name: A string type variable name
• Return Value: Boolean type (true indicates defined)
• Error: Throws an exception if the number of parameters is not 1

7. has

• Function: Check if a variable is defined in the current scope
• Parameters: (has name)
  • name: A string type variable name
• Return Value: Boolean type (true indicates defined)
• Error: Throws an exception if the number of parameters is not 1

List of Environment Variable Related Functions

1. err_codes

• Function: Get the runtime error code table
• Parameters: None
• Return Value: A hash table containing a mapping of (error code → description)
• Usage: Query error types during debugging

2. quote

• Function: Create a reference to an expression (prevent evaluation)
• Parameters: (quote expr)
  • expr: Any expression
• Return Value: Quote type (contains an immutable reference to the original expression)
• Error: Throws an exception if the number of parameters is not 1

3. print_tty

• Function: Write control instructions to tty
• Parameters: (print_tty expr)
  • String: Character expression
• Return Value: None type
• Error: Throws an exception if the number of parameters is not 1

4. discard

• Function: Send data to /dev/null
• Parameters: (discard expr)
  • expr: Any expression
• Return Value: Quote type (contains an immutable reference to the original expression)