u8-list->bytevector(3scm)

💅 u8-list->bytevector(3scm) — Scheme Programmer's Manual 💅

okay so welcome to the Scheme Programmer's Manual, section 3scm, bestie! This is the group chat for u8-list->bytevector, sint-list->bytevector, and uint-list->bytevector. 🫶

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🌸 NAME 🌸

Bestie, listen: u8-list->bytevector, sint-list->bytevector, and uint-list->bytevector are the little conversion crew that turns a list of integers into a bytevector. Iconic behavior, honestly. ✨

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🎀 LIBRARY 🎀

(import (rnrs))                     ;R6RS
(import (rnrs bytevectors))         ;R6RS

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🦋 SYNOPSIS 🦋

(u8-list->bytevector list)
(sint-list->bytevector list endianness size)
(uint-list->bytevector list endianness size)

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💖 DESCRIPTION 💖

So here's the vibe: these procedures convert a list of exact integers to a bytevector according to size and endianness. The integers are encoded in the same order as they appear in list. No cap. 🧚

The sint-list->bytevector procedure uses the two's complement representation, and uint-list->bytevector is for unsigned integers. Slay. 💜

The u8-list->bytevector procedure is the same as bytevector->uint-list with a size of 1. yes bestie, that is literally what the page says 👑

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⭐ RETURN VALUES ⭐

Returns a newly allocated bytevector. New, fresh, glowing. ✨

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🍓 EXAMPLES 🍓

Not me putting the whole serve in a code block: 💅

       (u8-list->bytevector '(1 2 3))
                 => #vu8(1 2 3)

       (uint-list->bytevector '(#xAA55 #x55AA #x4200) (endianness big) 2)
                 => #vu8(#xAA #x55 #x55 #xAA #x42 #x0)

       (sint-list->bytevector '(-2 -1 0 1 2) (endianness little) 1)
                 => #vu8(254 255 0 1 2)

       (let ((b (u8-list->bytevector '(1 2 3 255 1 2 1 2))))
         (bytevector->sint-list b (endianness little) 2))
                 => (513 -253 513 513)

       (let ((b (u8-list->bytevector '(1 2 3 255 1 2 1 2))))
         (bytevector->uint-list b (endianness little) 2))
                 => (513 65283 513 513)

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🌈 COMPATIBILITY 🌈

Tiny compatibility tea: the u8-list->bytevector procedure is absent from R7RS-small. You can use the bytevector(3scm) procedure instead, but it uses a variable argument list, which is usually less efficient. The other procedures have no equivalent in R7RS-small. iykyk 😭

⚠️ Also: if the returned bytevector would be empty then the returned bytevector does not have to be newly allocated. Important little caveat, bestie.

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💀 ERRORS 💀

This procedure can raise exceptions with the following condition types:

• &assertion (R6RS) — The wrong number of arguments was passed or an argument was outside its domain.

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👑 SEE ALSO 👑

• make-bytevector(3scm)
• bytevector->u8-list(3scm)
• bytevector(3scm)
• endianness(7scm)

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🌟 STANDARDS 🌟

R6RS. Periodt. 💅

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🦋 HISTORY 🦋

These procedures are new for R6RS, where they were based on SRFI-74. We love a documented origin story. ✨

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🫶 AUTHORS 🫶

This page is part of the scheme-manpages project. It includes materials from the RnRS documents. More information can be found at https://github.com/schemedoc/manpages/.

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Source/version check: this cutie is from the Scheme Programmer's Manual, page u8-list->bytevector(3scm), dated 2021-03-06. Bye bestie! 💖🦋💅