SCM Builtins

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SCM Builtins

The SCM Builtins module provides the core foundational functions for the SCM (Scheme) programming language implementation. These built-in functions handle essential operations including:

  • Language constructs: Control flow (if, and, or), variable management (define, set), and code evaluation (eval, quote)
  • Function operations: Lambda creation, function application, and error handling (try, error)
  • Data manipulation: Type conversion (string, symbol), list operations, and pattern matching
  • Development tools: Code optimization, timing measurements, and debugging support
  • Execution control: Parallel processing, variable scoping, and source code annotation

This module forms the foundation upon which all other SCM functionality is built, providing the essential primitives needed for Scheme programming.

← Back to Full SCM API documentation

quote

returns a symbol or list without evaluating it

Allowed number of parameters: 1–1

Parameters:

  • symbol (symbol): symbol to quote

Returns: symbol

eval

executes the given scheme program in the current environment

Allowed number of parameters: 1–1

Parameters:

  • code (list): list with head and optional parameters

Returns: any

size

compute the memory size of a value

Allowed number of parameters: 1–1

Parameters:

  • value (any): value to examine

Returns: int

optimize

optimize the given scheme program

Allowed number of parameters: 1–1

Parameters:

  • code (list): list with head and optional parameters

Returns: any

time

measures the time it takes to compute the first argument

Allowed number of parameters: 1–2

Parameters:

  • code (any): code to execute
  • label (string): label to print in the log or trace

Returns: any

if

checks a condition and then conditionally evaluates code branches; there might be multiple condition+true-branch clauses

Allowed number of parameters: 2–1000

Parameters:

  • condition... (bool): condition to evaluate
  • true-branch... (returntype): code to evaluate if condition is true
  • false-branch (returntype): code to evaluate if condition is false

Returns: returntype

and

returns true if all conditions evaluate to true

Allowed number of parameters: 1–1000

Parameters:

  • condition (bool): condition to evaluate

Returns: bool

or

returns true if at least one condition evaluates to true

Allowed number of parameters: 1–1000

Parameters:

  • condition (any): condition to evaluate

Returns: bool

coalesce

returns the first value that has a non-zero value

Allowed number of parameters: 1–1000

Parameters:

  • value (returntype): value to examine

Returns: returntype

coalesceNil

returns the first value that has a non-nil value

Allowed number of parameters: 1–1000

Parameters:

  • value (returntype): value to examine

Returns: returntype

define

defines or sets a variable in the current environment

Allowed number of parameters: 2–2

Parameters:

  • variable (symbol): variable to set
  • value (returntype): value to set the variable to

Returns: bool

set

defines or sets a variable in the current environment

Allowed number of parameters: 2–2

Parameters:

  • variable (symbol): variable to set
  • value (returntype): value to set the variable to

Returns: bool

error

halts the whole execution thread and throws an error message

Allowed number of parameters: 1–1000

Parameters:

  • value... (any): value or message to throw

Returns: string

try

tries to execute a function and returns its result. In case of a failure, the error is fed to the second function and its result value will be used

Allowed number of parameters: 2–2

Parameters:

  • func (func): function with no parameters that will be called
  • errorhandler (func): function that takes the error as parameter

Returns: any

apply

runs the function with its arguments

Allowed number of parameters: 2–2

Parameters:

  • function (func): function to execute
  • arguments (list): list of arguments to apply

Returns: any

apply_assoc

runs the function with its arguments but arguments is a assoc list

Allowed number of parameters: 2–2

Parameters:

  • function (func): function to execute (must be a lambda)
  • arguments (list): assoc list of arguments to apply

Returns: symbol

symbol

returns a symbol built from that string

Allowed number of parameters: 1–1

Parameters:

  • value (string): string value that will be converted into a symbol

Returns: symbol

list

returns a list containing the parameters as alements

Allowed number of parameters: 0–10000

Parameters:

  • value... (any): value for the list

Returns: list

string

converts the given value into string

Allowed number of parameters: 1–1

Parameters:

  • value (any): any value

Returns: string

match

takes a value evaluates the branch that first matches the given pattern

Patterns can be any of:

  • symbol matches any value and stores is into a variable
  • "string" (matches only this string)
  • number (matches only this value)
  • (symbol "something") will only match the symbol 'something'
  • '(subpattern subpattern...) matches a list with exactly these subpatterns
  • (concat str1 str2 str3) will decompose a string into one of the following patterns: "prefix" variable, variable "postfix", variable "infix" variable
  • (cons a b) will reverse the cons function, so it will match the head of the list with a and the rest with b
  • (regex "pattern" text var1 var2...) will match the given regex pattern, store the whole string into text and all capture groups into var1, var2...

Allowed number of parameters: 3–10000

Parameters:

  • value (any): value to evaluate
  • pattern... (any): pattern
  • result... (returntype): result value when the pattern matches; this code can use the variables matched in the pattern
  • default (any): (optional) value that is returned when no pattern matches

Returns: any

lambda

returns a function (func) constructed from the given code

Allowed number of parameters: 2–3

Parameters:

  • parameters (symbol|list|nil): if you provide a parameter list, you will have named parameters. If you provide a single symbol, the list of parameters will be provided in that symbol
  • code (any): value that is evaluated when the lambda is called. code can use the parameters provided in the declaration as well es the scope above
  • numvars (number): number of unnamed variables that can be accessed via (var 0) (var 1) etc.

Returns: func

begin

creates a own variable scope, evaluates all sub expressions and returns the result of the last one

Allowed number of parameters: 0–10000

Parameters:

  • expression... (any): expressions to evaluate

Returns: any

parallel

executes all parameters in parallel and returns nil if they are finished

Allowed number of parameters: 1–10000

Parameters:

  • expression... (any): expressions to evaluate in parallel

Returns: any

source

annotates the node with filename and line information for better backtraces

Allowed number of parameters: 4–4

Parameters:

  • filename (string): Filename of the code
  • line (number): Line of the code
  • column (number): Column of the code
  • code (returntype): code

Returns: returntype

scheme

parses a scheme expression into a list

Allowed number of parameters: 1–2

Parameters:

  • code (string): Scheme code
  • filename (string): optional filename

Returns: any

serialize

serializes a piece of code into a (hopefully) reparsable string; you shall be able to send that code over network and reparse with (scheme)

Allowed number of parameters: 1–1

Parameters:

  • code (list): Scheme code

Returns: string

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