### Test File Format Example

Source: https://github.com/gnome/gimp/blob/master/plug-ins/python/tests/test-file-plug-ins/README.md

Example of a .files format used to list images for testing, including optional expected results like EXPECTED_FAIL or SKIP.

```text
badbitcount.bmp, EXPECTED_FAIL
badbitssize.bmp
baddens1.bmp
baddens2.bmp, SKIP
```

--------------------------------

### BMP Test Configuration Example

Source: https://github.com/gnome/gimp/blob/master/plug-ins/python/tests/test-file-plug-ins/README.md

Example of a per-format configuration file for testing BMP files. It specifies enabled tests, descriptions, data folders, and associated files.

```ini
[test-1]
enabled=True
description=Test loading bmpsuite good images
folder=bmp/bmpsuite/g/
files=bmpsuite-g-tests.files
source=https://github.com/jsummers/bmpsuite
```

--------------------------------

### TinyScheme Standalone Usage Examples

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Demonstrates command-line usage for the TinyScheme interpreter, including help, file processing, and executing Scheme commands directly.

```shell
tinyscheme -?
```

```shell
tinyscheme [<file1> <file2> ...]
```

```shell
-1 <file> [<arg1> <arg2> ...]
```

```shell
-c <Scheme commands> [<arg1> <arg2> ...]
```

--------------------------------

### Example of TinyScheme Exception Handling

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Demonstrates the use of 'catch' and 'throw' for handling potential errors, such as division by zero, within a Scheme program.

```scheme
(define (foo x) (write x) (newline) (/ x 0))

 (catch (begin (display "Error!\n") 0)
      (write "Before foo ... ")
      (foo 5)
      (write "After foo"))
```

--------------------------------

### Convert MIT Scheme Example to GIMP Test

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/test/tests/readme.md

Convert examples from the MIT Scheme Reference into GIMP's testing framework format using the assert function. Ensure the left and right-hand sides of the MIT spec are correctly placed within the assert call.

```scheme
(assert '(equal?
            (vector 'a 'b 'c)
            #(a b c)))
```

--------------------------------

### Define Character Literals

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Shows examples of character literals, including space and newline, and hexadecimal/octal representations for string literals.

```scheme
#\space
```

```scheme
#\newline
```

--------------------------------

### Execute Scheme Script with #! Shebang

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Example of using the '-1' flag with a shebang line in a script to execute Scheme code, passing arguments to the script.

```scheme
#! /somewhere/tinyscheme -1
 (display *args*)
```

--------------------------------

### Find GIMP PDB Procedures Tested

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/test/tests/readme.md

This command-line snippet helps identify GIMP PDB procedures that are called within the test suite. It navigates to the PDB test directory, finds all .scm files, extracts procedure names starting with 'gimp-', sorts them, and lists unique entries.

```bash
>cd test/tests/PDB
>find . -name "*.scm" -exec grep -o "gimp-[a-z\-]*" {} \; | sort | uniq
```

--------------------------------

### Python 3 Unit Test Structure

Source: https://github.com/gnome/gimp/blob/master/libgimp/tests/README.md

Add Python 3 unit tests using this structure. Utilize gimp_assert() for assertions and ensure the file starts with the correct shebang.

```python
#!/usr/bin/env python3

# Add your test code here.
# Then test that it succeeded with the assert-like test:
gimp_assert('Test name for easy debugging', testme > 0)

# Repeat with more tests as needed.
```

--------------------------------

### Get the size of a file in TinyScheme

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/ftx/ftx-functions.txt

Use `file-size` to retrieve the size of a file in bytes. Returns #f if the file does not exist or is inaccessible.

```scheme
(file-size filename)
```

--------------------------------

### Read a directory entry in TinyScheme

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/ftx/ftx-functions.txt

Use `dir-read-entry` to get the name of the next entry in a directory stream. Returns `eof` when all entries are read.

```scheme
(dir-read-entry dirstream)
```

--------------------------------

### Get the type of a file in TinyScheme

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/ftx/ftx-functions.txt

Use `file-type` to get the type of a file (regular, directory, link, or other). Returns FILE_TYPE_OTHER (0) for non-existent files or insufficient privileges.

```scheme
(file-type filename)
```

--------------------------------

### Check if All Tests Passed

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/test/tests/readme.md

Use the `testing:all-passed?` predicate to get a boolean indicating the overall testing framework state.

```scheme
(testing:all-passed?)
```

--------------------------------

### Define a C Foreign Function for TinyScheme

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Example of a C function that squares its numeric argument. Foreign functions must accept a `scheme *sc` and `pointer args`, and return a `pointer`.

```c
pointer square(scheme *sc, pointer args) {
   if(args!=sc->NIL) {
       if(sc->isnumber(sc->pair_car(args))) {
            double v=sc->rvalue(sc->pair_car(args));
            return sc->mk_real(sc,v*v);
       }
   }
   return sc->NIL;
  }
```

--------------------------------

### Get time of day in microseconds in TinyScheme

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/ftx/ftx-functions.txt

The `gettimeofday` function returns a list containing seconds from the beginning of the day and microseconds within the current second.

```scheme
(gettimeofday)
```

--------------------------------

### Get Memory Block Length in GIMP Scheme

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/hack.txt

Retrieves the length of a given memory block. It checks if the provided argument is indeed a memory block.

```c
case OP_BLOCKLEN:  /* block-length */
         if(!ismemblock(car(sc->args))) {
              Error_1(sc,"block-length: not a memory block:",car(sc->args));
         }
         s_return(sc,mk_integer(sc,keynum(car(sc->args))));
```

--------------------------------

### Get current local time in TinyScheme

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/ftx/ftx-functions.txt

The `time` function returns the current local time as a list: (year month day-of-month hour min sec millisec). Year is an offset from 1900.

```scheme
(time)
```

--------------------------------

### Create a directory in TinyScheme

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/ftx/ftx-functions.txt

Use `dir-make` to create a new directory. An optional mode argument can specify permissions. Returns #t on success, #f on failure (e.g., directory exists, insufficient permissions).

```scheme
(dir-make dirname . mode)
```

--------------------------------

### Load a Test Script in GIMP

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/test/tests/readme.md

To run tests, load the desired test script using the SF Console. Ensure GIMP is a non-stable build.

```scheme
(testing:load-test "tinyscheme.scm")
```

--------------------------------

### GIMP Package Definition and Usage

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Demonstrates defining a package and accessing its members using the colon qualifier syntax. Requires USE_COLON_HOOK=1.

```scheme
(define toto
     (package
          (define foo 1)
          (define bar +)))

foo                                     ==>  Error, "foo" undefined
(eval 'foo)                             ==>  Error, "foo" undefined
(eval 'foo toto)                        ==>  1
toto::foo                               ==>  1
((eval 'bar toto) 2 (eval 'foo toto))   ==>  3
(toto::bar 2 toto::foo)                 ==>  3
(eval (bar 2 foo) toto)                 ==>  3
```

--------------------------------

### Scheme Reference - Environments

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Documentation for environment-related functions in TinyScheme.

```APIDOC
## Scheme Reference - Environments

### (interaction-environment)

Returns the interaction environment. In TinyScheme, this is an immutable list of association lists.

### (current-environment)

Returns the environment in effect at the time of the call. This can be used to define local environments, as shown in the `package` macro example in `init.scm`.

### (defined? <symbol>) (defined? <symbol> <environment>)

Checks whether the given symbol is defined in the current or a specified environment.
```

--------------------------------

### Run File Import Tests from Terminal

Source: https://github.com/gnome/gimp/blob/master/plug-ins/python/tests/test-file-plug-ins/README.md

Execute file import tests from the command line by piping a Python script to gimp-console. Configure necessary environment variables like PYTHONPATH, GIMP_TESTS_CONFIG_FILE, GIMP_TESTS_LOG_FILE, and GIMP_TESTS_DATA_FOLDER.

```bash
# Mandatory - the python script is passed via pipe to stdin and the python interpreter
# therefore cannot depend on __file__ and __name__ variables to establish the environment,
# this is especially important here, where it imports external modules.
export PYTHONPATH="/location/of/your/python/script/"

# Optional
export GIMP_TESTS_CONFIG_FILE="/location/of/config.ini" # Default: ./tests/config.ini
export GIMP_TESTS_LOG_FILE="/location/of/logfile.log"   # Default: ./tests/gimp-tests.log
export GIMP_TESTS_DATA_FOLDER="/location/of/test-images/rootfolder/" # Default: ./tests/

cd location/of/plug-in/gimp-file-plugin-tests
cat batch-import-tests.py | gimp-console-2.99 -idf --batch-interpreter python-fu-eval -b - --quit
```

--------------------------------

### Run File Import Tests with Flatpak

Source: https://github.com/gnome/gimp/blob/master/plug-ins/python/tests/test-file-plug-ins/README.md

Execute file import tests for the Flatpak version of GIMP. Environment variables like PYTHONPATH and GIMP_TESTS_DATA_FOLDER are passed using the --env flag.

```bash
cd location/of/plug-in/gimp-file-plugin-tests
cat batch-import-tests.py | flatpak run \
  --env=PYTHONPATH=$(pwd) \
  --env=GIMP_TESTS_DATA_FOLDER=<folder-with-test-data> \
  --env=GIMP_TESTS_CONFIG_FILE=$(pwd)/tests/batch-config.ini \
  org.gimp.GIMP -idf --batch-interpreter=python-fu-eval -b - --quit
```

--------------------------------

### Scheme Initialization

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

The interpreter state is initialized with the 'scheme_init' procedure.

```scheme
scheme_init
```

--------------------------------

### Download GIMP Test Images

Source: https://github.com/gnome/gimp/blob/master/plug-ins/python/tests/test-file-plug-ins/README.md

Clone the GIMP test images repository and set the GIMP_TESTS_DATA_FOLDER environment variable to point to the downloaded data.

```bash
git clone git@ssh.gitlab.gnome.org:Infrastructure/gimp-test-images.git <folder-with-test-data>

# as for convenience, during the tests, you can point at <folder-with-test-data> like

export GIMP_TESTS_DATA_FOLDER=<folder-with-test-data>
```

--------------------------------

### TinyScheme Overview

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

General information about TinyScheme, its purpose, and licensing.

```APIDOC
## TinyScheme Overview

### Description
TinyScheme is a lightweight Scheme interpreter designed for embedding into other programs. It implements a significant subset of R5RS, balancing features with a small footprint. It allows for multiple interpreter states and easy integration of C foreign functions.

### License
This software is open source, covered by a BSD-style license. Please read the accompanying file COPYING.

### Based On
This Scheme interpreter is based on MiniSCHEME version 0.85k4.
```

--------------------------------

### C Unit Test Structure

Source: https://github.com/gnome/gimp/blob/master/libgimp/tests/README.md

Use this template for C unit tests. Each test must be enclosed by GIMP_TEST_START() and GIMP_TEST_END() macros, followed by GIMP_TEST_RETURN.

```c
static GimpValueArray *
gimp_c_test_run (GimpProcedure        *procedure,
                 GimpRunMode           run_mode,
                 GimpImage            *image,
                 gint                  n_drawables,
                 GimpDrawable        **drawables,
                 GimpProcedureConfig  *config,
                 gpointer              run_data)
{
  /* Each test must be surrounded by GIMP_TEST_START() and GIMP_TEST_END()
   * macros this way:
   */
  GIMP_TEST_START("Test name for easy debugging")
  /* Run some code and finish by an assert-like test. */
  GIMP_TEST_END(testme > 0)

  /* Do more tests as needed. */

  /* Mandatorily end the function by this macro: */
  GIMP_TEST_RETURN
}
```

--------------------------------

### Scheme Oblist and Macro Expansion

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Provides access to the oblist (all symbols) and allows for macro expansion.

```scheme
(oblist)
(macro-expand <form>)
```

--------------------------------

### Open a directory stream in TinyScheme

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/ftx/ftx-functions.txt

Use `dir-open-stream` to open a directory stream for reading entries. Remember to close the stream with `dir-close-stream`.

```scheme
(dir-open-stream path)
```

--------------------------------

### Define Package Macro

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

This macro defines a package, allowing for local definitions within a closure. It returns the current environment.

```scheme
(macro (package form)
               `(apply (lambda () 
                         ,@(cdr form) 
                         (current-environment))))
```

--------------------------------

### Scheme Reference - Directives

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Documentation for interpreter control directives in TinyScheme.

```APIDOC
## Scheme Reference - Directives

### (gc)

Performs garbage collection immediately.

### (gcverbose) (gcverbose <bool>)

Controls whether garbage collection produces visible output. Defaults to `#t`.

### (quit) (quit <num>)

Stops the interpreter and sets the internal `retcode` field. Defaults to `0`. This value is returned as the exit code to the OS when the interpreter is run standalone.

### (tracing <num>)

Turns tracing on (`1`) or off (`0`). This functionality is conditional on `USE_TRACING` being enabled.
```

--------------------------------

### Scheme Reference - Supported Types

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Overview of data types supported by TinyScheme.

```APIDOC
## Scheme Reference - Supported Types

TinyScheme supports the following data types:
- Numbers (integers and reals)
- Symbols
- Pairs
- Strings
- Characters
- Ports
- Eof object
- Environments
- Vectors
```

--------------------------------

### Check if a file exists in TinyScheme

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/ftx/ftx-functions.txt

Use `file-exists?` to determine if a file exists and is accessible. Accessibility is based on real user/group IDs.

```scheme
(file-exists? filename)
```

--------------------------------

### Scheme Reference - Literals

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Details on string and character literal syntax in TinyScheme.

```APIDOC
## Scheme Reference - Literals

### String Literals
String literals can contain escaped quotes (`\") as usual. They also support escape sequences for newline (`\n`), carriage return (`\r`), tab (`\t`), hexadecimal representations (`\xDD`), and octal representations (`\DDD`). Literal newlines are also permitted within string literals, functioning similarly to HERE-strings.

Example:
```scheme
(define s "String with newline here
and here
that can function like a HERE-string")
```

### Character Literals
Character literals include standard characters like `#\space` and `#\newline`.
```

--------------------------------

### Scheme Reference - Symbols

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Documentation for symbol manipulation in TinyScheme.

```APIDOC
## Scheme Reference - Symbols

### (gensym)

Returns a new interned symbol each time it is called. This function might be moved to the library once `string->symbol` is implemented.
```

--------------------------------

### File System Functions

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/ftx/ftx-functions.txt

Functions for interacting with the file system, including checking file existence, type, size, deletion, and directory operations.

```APIDOC
## File System Functions

### Description
Provides functions for interacting with the file system.

### Functions

#### `file-exists?`

##### Description
Checks if a file exists and is accessible.

##### Parameters
- **filename** (string) - The path to the file.

##### Returns
- `#t` if the file exists and is accessible, `#f` otherwise.

#### `file-type`

##### Description
Determines the type of a file.

##### Parameters
- **filename** (string) - The path to the file.

##### Returns
- `FILE_TYPE_FILE` (1) for regular files.
- `FILE_TYPE_DIR` (2) for directories.
- `FILE_TYPE_LINK` (3) for symbolic links.
- `FILE_TYPE_OTHER` (0) if the file type cannot be determined or the file does not exist.

#### `file-size`

##### Description
Gets the size of a file in bytes.

##### Parameters
- **filename** (string) - The path to the file.

##### Returns
- The size of the file in bytes, or `#f` if the file does not exist or is not accessible.

#### `file-delete`

##### Description
Removes a file.

##### Parameters
- **filename** (string) - The path to the file to delete.

##### Returns
- `#t` if the operation succeeds, `#f` otherwise.

#### `dir-open-stream`

##### Description
Opens a directory stream for reading directory entries.

##### Parameters
- **path** (string) - The path to the directory.

##### Returns
- A directory stream object.

#### `dir-read-entry`

##### Description
Reads the next entry from a directory stream.

##### Parameters
- **dirstream** (directory stream) - The directory stream obtained from `dir-open-stream`.

##### Returns
- The name of the next directory entry, or `eof` if all entries have been read.

#### `dir-rewind`

##### Description
Resets a directory stream to the beginning.

##### Parameters
- **dirstream** (directory stream) - The directory stream to rewind.

##### Returns
- `#t` if the operation succeeds, `#f` otherwise.

#### `dir-close-stream`

##### Description
Closes a directory stream.

##### Parameters
- **dirstream** (directory stream) - The directory stream to close.

#### `dir-make`

##### Description
Creates a new directory.

##### Parameters
- **dirname** (string) - The name of the directory to create.
- **mode** (integer, optional) - Permissions for the new directory.

##### Returns
- `#t` if the operation succeeds, `#f` otherwise.
```

--------------------------------

### TinyScheme Sharp Hook for Reader Extensions

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Defines a procedure '*sharp-hook*' that is called when the reader encounters an unknown character following '#'. This allows for custom syntax.

```scheme
*sharp-hook*
```

--------------------------------

### Scheme Reference - Mathematical Functions

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Details on supported mathematical functions in TinyScheme.

```APIDOC
## Scheme Reference - Mathematical Functions

### Supported Functions
Due to the absence of rational and complex numbers, corresponding functions are also missing. Supported functions include:
- `exp`, `log`, `sin`, `cos`, `tan`, `asin`, `acos`, `atan`, `floor`, `ceiling`, `trunc`, `round`
- `sqrt`, `expt` (when `USE_MATH=1`)
- Number-theoretical quotient, remainder, modulo, `gcd`, `lcm`

### Library Functions
- `exact?`, `inexact?`, `odd?`, `even?`, `zero?`, `positive?`, `negative?`
- `exact->inexact`
- `inexact->exact` (core function)
```

--------------------------------

### Scheme List and Pair Operations

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Core procedures for constructing and manipulating lists and pairs, including mapping, folding, and appending.

```scheme
cons
car
cdr
list
length
map
for-each
foldr
list-tail
list-ref
last-pair
reverse
append
member
memq
memv
assoc
assq
assv
```

--------------------------------

### Scheme Reference - Type Predicates

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

List of type predicate functions available in TinyScheme.

```APIDOC
## Scheme Reference - Type Predicates

TinyScheme supports the following type predicate functions:
- `boolean?`
- `eof-object?`
- `symbol?`
- `number?`
- `string?`
- `integer?`
- `real?`
- `list?`
- `null?`
- `char?`
- `port?`
- `input-port?`
- `output-port?`
- `procedure?`
- `pair?`
- `environment?`
- `vector?`
- `closure?`
- `macro?`
```

--------------------------------

### Scheme Dynamic Extension Loading

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Loads dynamically linked extensions, allowing for the integration of foreign procedures.

```scheme
(load-extension <filename without extension>)
```

--------------------------------

### Format Memory Block for Printing

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/hack.txt

Add a case to `atom2str` to format memory blocks for printing, displaying them as '#<MEMBLOCK>'.

```c
else if (ismemblock(l)) {
         p = "#<MEMBLOCK>";
```

--------------------------------

### Make Memory Block in GIMP Scheme

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/hack.txt

Creates a new memory block of a specified length, optionally filled with a character. Handles invalid input for length and fill character.

```c
case OP_MKBLOCK: {
         int fill=0;
         int len;

         if(!isnumber(car(sc->args))) {
              Error_1(sc,"make-block: not a number:",car(sc->args));
         }
         len=ivalue(car(sc->args));
         if(len<=0) {
              Error_1(sc,"make-block: not positive:",car(sc->args));
         }

         if(cdr(sc->args)!=sc->NIL) {
              if(!isnumber(cadr(sc->args)) || ivalue(cadr(sc->args))<0) {
                   Error_1(sc,"make-block: not a positive number:",cadr(sc->args));
              }
              fill=charvalue(cadr(sc->args))%255;
         }
         s_return(sc,mk_memblock(sc,len,(char)fill));
     }
```

--------------------------------

### Known Issues and Missing Features

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Details on known bugs and features that are not implemented in TinyScheme.

```APIDOC
## Known Issues and Missing Features

### Known Bugs
TinyScheme is known to misbehave when memory is exhausted.

### Missing Features
- Hygienic macros
- Rational and complex numbers
- unwind-protect and call-with-values
- Decent debugging facilities (only tracing is supported natively)

### Potential Enhancements
- Subset of SLIB might work with TinySCHEME.
- String->symbol implementation is pending.
```

--------------------------------

### Scheme Define with Return

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

A variant of 'define' that makes the continuation available as 'return' within the procedure, useful for imperative programming.

```scheme
(define-with-return (<procname> <args>...) <body>)
```

--------------------------------

### Scheme String Port Operations

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Enables I/O operations using strings as ports, facilitating reading from and writing to string buffers.

```scheme
open-input-string
open-output-string
get-output-string
open-input-output-string
```

--------------------------------

### TinyScheme Catch Exception Block

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Establishes a scope for exception handling. Any expression within the 'catch' block that throws an exception will be caught, and the first argument to 'catch' will be evaluated.

```scheme
(catch <expr returned exceptionally>
     <expr1> <expr2> ... <exprN>)
```

--------------------------------

### Scheme String Operations

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Offers a comprehensive set of procedures for string manipulation, including creation, length, element access, substring extraction, and comparison.

```scheme
string
make-string
list->string
string-length
string-ref
string-set!
substring
string->list
string-fill!
string-append
string-copy
string=?
string<?
string>?
string<=?
string>=?
string->number
number->string
atom->string
string->atom
```

--------------------------------

### Create New Memory Block Function

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/hack.txt

Implement the `mk_memblock` function to create a new memory block of a specified length, optionally filled with a byte. It handles memory allocation and initialization.

```c
static pointer mk_memblock(scheme *sc, int len, char fill) {
         pointer x;
         char *p=(char*)sc->malloc(len);

         if(p==0) {
              return sc->NIL;
         }
         x = get_cell(sc, sc->NIL, sc->NIL);

         typeflag(x) = T_MEMBLOCK|T_ATOM;
         strvalue(x)=p;
         keynum(x)=len;
         memset(p,fill,len);
         return (x);
    }
```

--------------------------------

### Unit Test Assertion

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/test/tests/readme.md

Use `assert` for normal operation unit tests in the testing framework.

```scheme
assert
```

--------------------------------

### Suspend execution in microseconds in TinyScheme

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/ftx/ftx-functions.txt

Use `usleep` to pause the current thread for a specified number of microseconds.

```scheme
(usleep microsec)
```

--------------------------------

### Define a Foreign Function in TinyScheme Environment

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Registers a C foreign function named 'square' into the global environment of the TinyScheme interpreter. Ensure the 'square' C function is defined and accessible.

```scheme
sc->interface->scheme_define(
        sc,
        sc->global_env,
        sc->interface->mk_symbol(sc,"square"),
        sc->interface->mk_foreign_func(sc, square));
```

--------------------------------

### Configure Error Line Display in TinyScheme

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/test/tests/readme.md

Modify the `SHOW_ERROR_LINE` macro in `libscriptfu/tinyscheme/scheme.h` to control line number display in error messages. Setting it to `0` is recommended for portable error testing.

```c
# define SHOW_ERROR_LINE 0
```

--------------------------------

### Scheme Closure Operations

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Procedures for retrieving the code of a closure and for creating new closures within a specified environment.

```scheme
(get-closure-code <closure>)
(make-closure <code> <environment>)
```

--------------------------------

### Scheme Memory Allocation

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Allows for dynamic allocation of additional memory segments.

```scheme
(new-segment <num>)
```

--------------------------------

### Close a directory stream in TinyScheme

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/ftx/ftx-functions.txt

Use `dir-close-stream` to close an open directory stream. No further `dir-read-entry` calls should be made after closing.

```scheme
(dir-close-stream dirstream)
```

--------------------------------

### Define Custom Error Hook in TinyScheme

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Sets the '*error-hook*' variable to the 'throw' procedure, enabling a custom exception handling mechanism for system errors.

```scheme
(define *error-hook* throw)
```

--------------------------------

### Scheme Stream Operations

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Procedures for working with streams, including accessing their head and tail, and constructing new streams.

```scheme
head
tail
cons-stream
```

--------------------------------

### Rewind a directory stream in TinyScheme

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/ftx/ftx-functions.txt

Use `dir-rewind` to reset a directory stream, allowing `dir-read-entry` to read from the beginning again. Returns #t on success, #f if the stream is invalid.

```scheme
(dir-rewind dirstream)
```

--------------------------------

### Scheme Vector Operations

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Provides functions for creating, manipulating, and querying vectors, including length, element access, and conversion to/from lists.

```scheme
make-vector
vector
vector-length
vector-ref
vector-set!
list->vector
vector-fill!
vector->list
vector-equal?
```

--------------------------------

### Scheme Property List Operations

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Procedures for managing property lists associated with symbols.

```scheme
put
get
```

--------------------------------

### Delete a file in TinyScheme

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/ftx/ftx-functions.txt

Use `file-delete` to remove a specified file. Returns #t on success, #f if the file is read-only or does not exist.

```scheme
(file-delete filename)
```

--------------------------------

### Define String Literal with Newlines

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Demonstrates defining a string literal that spans multiple lines, functioning similarly to a HERE-string.

```scheme
(define s "String with newline here
          and here
          that can function like a HERE-string")
```

--------------------------------

### Scheme Obsolete Procedure

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

An obsolete procedure for printing the width of an object.

```scheme
(print-width <object>)
```

--------------------------------

### Throw an Exception in TinyScheme

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Throws a custom exception with a given message. If used outside a 'catch' block, it reverts to the default 'error' behavior.

```scheme
(throw "message")
```

--------------------------------

### Scheme Symbol Conversion

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Procedures for converting between symbols and their string representations.

```scheme
symbol->string
string->symbol
```

--------------------------------

### Scheme Control Features

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Procedures related to control flow, including mapping, iteration, and continuation handling.

```scheme
procedure?
macro?
closure?
map
for-each
force
delay
call-with-current-continuation
eval
apply
```

--------------------------------

### Time Functions

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/ftx/ftx-functions.txt

Functions for retrieving and manipulating time information.

```APIDOC
## Time Functions

### Description
Provides functions for working with time.

### Functions

#### `time`

##### Description
Returns the current local time.

##### Returns
- A list of integers: `(year month day-of-month hour min sec millisec)`.
  - `year` is an offset from 1900.

#### `gettimeofday`

##### Description
Returns the current time in seconds and microseconds from the beginning of the day.

##### Returns
- A list containing: seconds from the beginning of the day, microseconds within the current second.

#### `usleep`

##### Description
Suspends execution for a specified number of microseconds.

##### Parameters
- **microsec** (integer) - The number of microseconds to sleep.

##### Returns
- None.
```

--------------------------------

### Unit Test Expected Runtime Error Assertion

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/test/tests/readme.md

Use `assert-error` for testing expected runtime errors in unit tests.

```scheme
assert-error
```

--------------------------------

### Define Helper Macro for Memory Block Check

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/hack.txt

Define a macro or function to check if a pointer refers to a memory block. This is useful for exported functions.

```c
#define is_memblock(p) (type(p)==T_MEMBLOCK)
```

--------------------------------

### Scheme Character Conversion

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Functions for converting between characters and their integer representations, and for character comparison.

```scheme
integer->char
char->integer
char=?
char<?
char>?
char<=?
char>=?
```

--------------------------------

### Reference Element in Memory Block in GIMP Scheme

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/hack.txt

Accesses and returns the character at a specific index within a memory block. Performs bounds checking and argument validation.

```c
case OP_BLOCKREF: { /* block-ref */
         char *str;
         int index;

         if(!ismemblock(car(sc->args))) {
              Error_1(sc,"block-ref: not a memory block:",car(sc->args));
         }
         str=strvalue(car(sc->args));

         if(cdr(sc->args)==sc->NIL) {
              Error_0(sc,"block-ref: needs two arguments");
         }
         if(!isnumber(cadr(sc->args))) {
              Error_1(sc,"block-ref: not a number:",cadr(sc->args));
         }
         index=ivalue(cadr(sc->args));

         if(index<0 || index>=keynum(car(sc->args))) {
              Error_1(sc,"block-ref: out of bounds:",cadr(sc->args));
         }

         s_return(sc,mk_integer(sc,str[index]));
     }
```

--------------------------------

### Scheme Numeric Literals

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Supports various numeric bases including hexadecimal (#x), octal (#o), binary (#b), and decimal (#d). Flonums are currently read-only in decimal.

```scheme
#x
#o
#b
#d
```

--------------------------------

### Scheme Character Literals

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Represents characters using #\ notation, supporting standard characters, control characters with ASCII names, and hex representations.

```scheme
#\return
#\tab
#\x20
#\space
```

--------------------------------

### Set External Data for Scheme Interpreter

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/Manual.txt

Sets external data for the Scheme interpreter. This function is used to associate custom data with the interpreter's state, accessible by foreign functions.

```c
void scheme_set_external_data(scheme *sc, void *p);
```

--------------------------------

### Check if Memory Block in GIMP Scheme

Source: https://github.com/gnome/gimp/blob/master/plug-ins/script-fu/libscriptfu/tinyscheme/hack.txt

Predicate function to determine if an argument is a memory block. Returns a boolean value.

```c
case OP_BLOCKP:     /* block? */
         s_retbool(ismemblock(car(sc->args)));
```