Nim Standard Library Documentation

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Overview

Author: Andreas Rumpf Version: 2.2.6

Nim's library ecosystem is organized into three categories: pure libraries (no external binary dependencies), impure libraries (requiring external binaries), and wrappers (low-level C library interfaces).

For additional packages, visit Nimble Directory.

Pure Libraries

Automatic Imports

system — Basic procs and operators that every program needs, with IO functionality. Imported implicitly; do not import directly.

Core

atomics — Atomic operations and lockless algorithms
bitops — Low-level bit manipulation methods
compilesettings — Compiler configuration querying
cpuinfo — CPU/core detection
effecttraits — Inferred .raises effects access
endians — Byte order handling
locks — Locks and condition variables
macrocache — Compile-time macro information collection
macros — AST API for macro writing
rlocks — Reentrant locks
typeinfo — Runtime type information access
typetraits — Compile-time type reflection
volatile — Volatile load/store generation

Algorithms

algorithm — Generic algorithms (sort, binary search)
enumutils — Enhanced enum functionality
sequtils — Functional programming operations for sequences
setutils — Enhanced set functionality

Collections

critbits — Crit bit tree for sorted strings/mappings
deques — Double-ended queue implementation
heapqueue — Binary heap/priority queue
intsets — Sparse bit set for integers
lists — Singly/doubly linked and circular lists
options — Optional value encapsulation
packedsets — Sparse bit set for ordinals
ropes — Efficient long string representation
sets — Hash set support
strtabs — String-to-string hash table with case modes
tables — Hash, ordered, and count tables

String Handling

cstrutils — C string utilities
editdistance — Unicode string edit distance
encodings — Character encoding conversion
formatfloat — Float-to-string formatting
objectdollar — Generic object-to-string operator
punycode — ASCII Unicode representation
strbasics — High-performance string operations
strformat — Python f-string style interpolation
strmisc — Uncommon string operations
strscans — scanf-style mini-language parsing
strutils — Common string operations (case, split, search, replace)
unicode — UTF-8 Unicode support
unidecode — Unicode-to-ASCII transliteration
widestrs — C/C++ wide string support
wordwrap — Unicode string word-wrapping

Time Handling

monotimes — Monotonic timestamp implementation
times — Time working and manipulation

Generic Operating System Services

appdirs — Special directory determination
cmdline — Command line parameter reading
dirs — Directory operations
distros — OS distribution detection and package manager basics
dynlib — Shared library symbol access
envvars — Environment variable operations
exitprocs — Program exit hooks
files — File operations
memfiles — Memory-mapped file support
os — Basic operating system facilities for environment, arguments, directories, and shell commands
oserrors — OS error reporting
osproc — Advanced process communication
paths — Path operations
reservedmem — Address space reservation without physical memory
streams — Stream interface with File and String implementations
symlinks — Symbolic link operations
syncio — Synchronized I/O operations
terminal — Terminal/console output control
tempfiles — Temporary file/directory creation

Math Libraries

complex — Complex numbers and operations
fenv — Floating-point environment and exception handling
lenientops — Mixed integer/float operators
math — Mathematical functions (cosine, square root, etc.)
random — Fast lightweight RNG
rationals — Rational numbers and operations
stats — Statistical analysis
sysrand — Cryptographically secure PRNG

Internet Protocols and Support

async — Exports asyncmacro, asyncfutures, and asyncjs
asyncdispatch — Asynchronous IO dispatcher
asyncfile — Async file operations via asyncdispatch
asyncftpclient — Async FTP client
asynchttpserver — Async HTTP server
asyncmacro — async and multisync macros
asyncnet — Async sockets via asyncdispatch
asyncstreams — FutureStream queue implementation
cgi — CGI application helpers
cookies — Cookie parsing and generation
httpclient — HTTP client with sync/async support
mimetypes — MIME type database
nativesockets — Low-level sockets API
net — High-level sockets API
selectors — OS-specific selector (epoll, kqueue, poll, select)
smtp — SMTP client with sync/async operation
socketstreams — Stream interface for sockets
uri — URI and URL functions

Threading

isolation — Isolated[T] for safe thread/channel passing
tasks — Parallel program primitives
threadpool — spawn implementation
typedthreads — Basic thread support

Parsers

htmlparser — HTML document parser to XML tree
json — High-performance JSON parser
lexbase — Efficient buffering for lexers/parsers
parsecfg — Configuration file parser (INI-like)
parsecsv — CSV parser
parsejson — JSON parser
parseopt — Command line option parser
parsesql — SQL parser
parseutils — Token, number, and identifier parsing helpers
parsexml — XML/HTML parser (UTF-8, error-correcting)
pegs — PEG procedures and operators

Docutils

packages/docutils/highlite — Source code highlighter
packages/docutils/rst — reStructuredText parser
packages/docutils/rstast — reStructuredText AST
packages/docutils/rstgen — HTML/LaTeX generator from reStructuredText

XML Processing

xmltree — Simple XML tree with code generation macro
xmlparser — XML document parser to tree representation

Generators

genasts — AST generation via captured variables
htmlgen — HTML/XML code generator with tag macros

Hashing

base64 — Base64 encoding/decoding
hashes — Efficient hash value computation
md5 — MD5 checksum algorithm
oids — Globally unique ID via timestamp, counter, random value
sha1 — SHA-1 checksum algorithm

Serialization

jsonutils — Hookable JSON (de)serialization
marshal — Nim data structure serialization/deserialization

Miscellaneous

assertions — Assertion handling
browsers — Default browser URL opening
colors — Color operations
coro — Experimental coroutines
decls — Declaration syntax sugar
enumerate — enumerate macro sugar
importutils — Import and symbol resolution utilities
logging — Simple logger
segfaults — Segfault-to-exception conversion
sugar — Syntactic sugar macros
unittest — Unit testing DSL
varints — SQLite-compatible variable-length integers
with — Function chaining macro
wrapnils — Safe nil dereference evaluation

JavaScript Backend Modules

asyncjs — Async types and macros for JavaScript
dom — Document Object Model declarations
jsbigints — Arbitrary precision integers
jsconsole — console object wrapper
jscore — Core JavaScript functions wrapper
jsfetch — fetch wrapper
jsffi — JavaScript interoperability types and macros
jsre — JavaScript regular expressions

Impure Libraries

Regular Expressions

re — Procedures and operators for handling regular expressions using PCRE
nre — Helper functions for regular expressions using PCRE

Database Support

db_mysql — MySQL wrapper with standard cross-database interface
db_odbc — ODBC wrapper with standard cross-database interface
db_postgres — PostgreSQL wrapper with standard cross-database interface
db_sqlite — SQLite wrapper with standard cross-database interface

Generic Operating System Services

rdstdin — User input reading from stdin

Wrappers

(Note: Some wrapper HTML documentation is too large for distribution; view on the website.)

Windows-Specific

winlean — Small Win32 API subset wrapper
registry — Windows registry support

UNIX-Specific

posix — POSIX standard wrapper
posix_utils — POSIX/Linux/BSD helpers

Regular Expressions

pcre — PCRE library wrapper

Database Support

mysql — MySQL API wrapper
odbcsql — ODBC driver interface
postgres — PostgreSQL API wrapper
sqlite3 — SQLite 3 API wrapper

Network Programming and Internet Protocols

openssl — OpenSSL wrapper

Source: nim-lang.org/docs/lib.html — Generated: 2025-10-31