YREA-SLS/docs/advanced_topics.md

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11 Advanced Topics	Generic Programming	Standard Library

11. Advanced Topics

11.1 Dynamic Code Evaluation

The eval operator executes code dynamically at runtime by parsing and executing a TokenString.

Syntax: { code } eval

Examples:

// Evaluate simple expression
"2 3 +" eval            // Pushes 5

// Build and execute code
"(Multiplyable -- Multiplyable) { dup * } ::square fn" eval
5 square                // 25

// Dynamic dispatch
operation_name " get" concat eval

Use Cases:

• Building code at runtime
• Dynamic dispatch based on runtime values
• Implementing interpreters or REPLs
• Meta-programming

Warnings:

• Eval introduces runtime overhead (parsing)
• Type safety is reduced (types checked at eval time, not compile time)
• Security risk if evaluating untrusted code
• Use sparingly and prefer static alternatives when possible

11.2 Identifier Literals

Identifier literals use the :: prefix to push an identifier as a value rather than executing it.

Syntax: ::name

Context-Dependent Rules:

In function bodies and eval: :: is required for identifier literals

::Point                 // Pushes identifier "Point"
::Addable              // Pushes identifier "Addable"

In trait definitions: :: is not allowed (identifiers are method names)

{
    (Self -- ) draw:    // "draw:" is a method name, not a literal
} ::Drawable trait

In trait implementations: :: is not allowed (identifiers are method names)

::Drawable {
    (Self -- ) { ... } draw:  // "draw:" is a method name
} ::Rectangle impl

Use Cases:

• Defining structs: (T T --) { x: y: } ::Point<T> struct
• Defining traits: { ... } ::Drawable trait
• Field access: point ::x get
• Dynamic trait operations
• Meta-programming

11.3 Standard Library

The standard library provides I/O, string operations, type conversions, and utility functions. All standard library functions are automatically in scope (no imports needed in current version).

I/O Operations:

"Hello" print           // Print string to stdout
"Enter name: " input    // Read line from stdin
"file.txt" read         // Read file contents as string
"data" "file.txt" write // Write string to file

String Operations:

"hello" " world" concat     // Concatenate strings
"hello" length              // Get string length
"hello" 1 3 substr          // Extract substring
"a,b,c" "," split           // Split by delimiter
["a" "b"] "," join          // Join with delimiter

Type Conversion:

42 to_f64               // Convert i32 to f64
3.14 to_i32             // Convert f64 to i32 (truncates)
"123" parse             // Parse string to inferred type
42 to_str               // Convert to string

Array Operations:

• Element access: at, slice
• Information: length, shape
• Combinators: map, filter, reduce, each
• Manipulation: concat, reverse, transpose, window

Complete Reference: See Appendix A for the full standard library reference with all functions, signatures, and examples.

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