Racket Cheat Sheet🔗 i

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Running Put #lang racket "Hello, world!" in hello.rkt and run racket hello.rkt

Literals integer 1 rational 1/2 complex 1+2i floating 3.14 double 6.02e+23 hex #x29 octal #o32 binary #b010101

Arithmetic + - * / quotient remainder modulo add1 sub1 max min round floor ceiling sqrt expt exp log sin ...atan

Compare = < <= > >=

Bitwise bitwise-ior bitwise-and bitwise-xor bitwise-not arithmetic-shift integer-length

Format number->string string->number real->decimal-string

Test number? complex? ...exact-nonnegative-integer? ...zero? positive? negative? even? odd? exact? inexact?

Misc random

Match Pattern (?number? n)42

Literals "Racket" quoting "a \" approaches!" unicode "λx:(μα.α→α).xx"

Create make-string string string-append build-string string-join

Observe string-length string-ref substring string-split in-string

Modify string-downcase string-upcase string-trim

Test string? string=? string<=? string-ci<=?

Regexp #rx"a|b"#rx"^c(a|d)+r$"regexp-quote regexp-match regexp-split regexp-replace regexp-replace*

Match Pattern (?string? s)"Banana?"

Literals #"rawbytes0円"

Create make-bytes bytes

Numbers integer->integer-bytes real->floating-point-bytes

Observe bytes-length bytes-ref subbytes in-bytes

Modify bytes-set! bytes-copy! bytes-fill!

Conversion bytes->string/utf-8
string->bytes/utf-8

Test bytes? bytes=?

Match Pattern (?bytes? b)#"0xDEADBEEF"

Booleans #t#fnot equal?

Characters #\a#\tab#\λchar? char->integer integer->char char<=? ...char-alphabetic? ...

Symbols 'Racketsymbol? eq? string->symbol gensym

Boxes box? box unbox set-box! box-cas!

Procedures procedure? apply compose compose1 keyword-apply procedure-rename procedure-arity curry arity-includes?

Void void? void

Undefined undefined

Create empty list list* build-list for/list

Observe empty? list? pair? length list-ref member count argmin argmax

Use append reverse map andmap ormap foldr in-list

Modify filter remove ...sort take drop split-at partition remove-duplicates shuffle

Match Pattern (list abc)(list* abmore)(list topmore...)

Create hash hasheq

Observe hash? hash-ref hash-has-key? hash-count in-hash in-hash-keys in-hash-values

Modify hash-set hash-update hash-remove

Create build-vector vector make-vector list->vector

Observe vector? vector-length vector-ref in-vector

Modify vector-set! vector-fill! vector-copy! vector-map!

Match Pattern (vector xyz)(vector xycalabi–yau...)

Create stream stream* empty-stream

Observe stream-empty? stream-first stream-rest in-stream

Create make-hash make-hasheq

Observe hash? hash-ref hash-has-key? hash-count in-hash in-hash-keys in-hash-values

Modify hash-set! hash-ref! hash-update! hash-remove!

Formatting ~a ~v ~s ~e ~r pretty-format

Input read read-bytes peek-byte

Output write write-bytes display displayln pretty-print

Ports and Files with-input-from-file with-output-to-file flush-output file-position make-pipe with-output-to-string with-input-from-string port->bytes port->lines ...

Paths build-path bytes->path path->bytes path-replace-suffix ...

Files file-exists? rename-file-or-directory copy-directory/files current-directory make-directory delete-directory/files directory-list filesystem-change-evt file->bytes file->lines make-temporary-file

Time current-seconds current-inexact-milliseconds date->string date-display-format

Command-Line Parsing command-line

FFI ffi-lib _uint32 ..._fun malloc free

TCP tcp-listen tcp-connect tcp-accept tcp-close

HTTP http-conn http-conn-open! http-conn-send! http-conn-recv! http-conn-sendrecv! http-sendrecv

URLs string->url url->string url-query

Email smtp-send-message imap-connect ...

JSON write-json read-json

XML read-xml write-xml write-xexpr

Databases postgresql-connect mysql-connect sqlite3-connect query-exec query-rows prepare start-transaction ...

Custodians make-custodian custodian-shutdown-all current-custodian

Sandboxes make-evaluator make-module-evaluator

Threads thread kill-thread thread-wait make-thread-group

Events sync choice-evt wrap-evt handle-evt alarm-evt ...

Channels make-channel channel-get channel-put

Semaphores make-semaphore semaphore-post semaphore-wait

Async Channels make-async-channel async-channel-get async-channel-put

Futures future touch processor-count make-fsemaphore ...

Places dynamic-place place place-wait place-wait place-channel ...

Processes subprocess system*

Modules (module+ mainbody...)
(module+ testbody...)
(require mod-path)(provide id)

S-expressions quote '(abc)quasiquote unquote `(12,(+ 12))

Procedure Applications (fnarg1arg2)
keyword args (fnarg1#:keyarg2)
(apply fnarg1(list arg2))

Procedures (lambda (x)x)(λ (x)x)
(λ (x[opt1])(+ xopt))
(λ (x#:reqkey)(+ xkey))
(λ (x#:opt[key1])(+ xkey))

Binding (let ([x1][y2])(+ xy))
(let* ([x1][x(+ x1)])x)

Conditionals (if (zero? x)0(/ 1x))
(cond [(even? x)0][(odd? x)1]
[else "impossible!"])
and or

Definitions (define x1)
(define (fy)(+ xy))

Iteration for for/list for*

Blocks begin when unless

Require Sub-forms prefix-in only-in except-in rename-in for-syntax for-label ...

Provide Sub-forms all-defined-out all-from-out rename-out ...contract-out

Definition (struct dillo(weightcolor))

Create (define danny(dillo17.5'purple))

Observe (dillo?danny)(dillo-weightdanny)(dillo-colordanny)

Modify (struct-copy dillodanny([weight18.0]))

Match Pattern (dillowc)

Basics (match value[patbody]...)

Definitions (match-define patvalue)

Patterns (quotedatum)(list lvp...)(list-no-orderpat...)(vectorlvp...)(struct-idpat...)(regexprx-exprpat)(orpat...)(andpat...)(?exprpat...)

Mutation set!

Exceptions error with-handlers raise exit

Promises promise? delay force

Continuations let/cc let/ec dynamic-wind call-with-continuation-prompt abort-current-continuation call-with-composable-continuation

Parameters make-parameter parameterize

External Files Needed at Runtime define-runtime-path

Continuation Marks continuation-marks with-continuation-mark continuation-mark-set->list

Multiple Values values let-values define-values call-with-values

Basics any/c or/c and/c false/c integer-in vector/c listof list/c ...

Functions -> ->* ->i

Application contract-out recontract-out with-contract define/contract

Sequences in-range in-naturals in-list in-vector in-port in-lines in-hash in-hash-keys in-hash-values in-directory in-cycle stop-before stop-after in-stream

Generators generator yield in-generator

Sub-structures (struct 2d(xy))(struct 3d2d(z))(2d-x(3d123))

Mutation (struct monster(type[hp#:mutable]))(define healie(monster'slime10))(set-monster-hp!healie0)

Transparency (struct cash($¢)#:transparent)(struct->vector (cash595))

Printing (struct nickname[nv]#:methodsgen:custom-write [(define (write-procnnpmode)(fprintf p(nickname-nnn)))])(displayln (nickname"evens"(in-range 01002)))

Serialization (struct txn(whowhatwhere)#:prefab)(write (txn"Mustard""Spatula""Observatory"))

Definition define-generics

Instantiation (struct even-set()#:methodsgen:set [(define (set-member? sti)(even? i))])

Definition interface class*

Instantiation make-object new instantiate

Methods send send/apply send/keyword-apply send* send+

Fields get-field set-field!

Mixins mixin

Traits trait trait-sum trait-exclude trait-rename ...

Contracts class/c instanceof/c is-a?/c implementation?/c subclass?/c

Definition define-syntax define-simple-macro begin-for-syntax for-syntax

Templates syntax syntax/loc with-syntax

Parsing ()-Syntax syntax-parse define-syntax-class pattern

Syntax Objects syntax-source syntax-line ...syntax->datum datum->syntax generate-temporaries format-id

Transformers make-set!-transformer make-rename-transformer local-expand syntax-local-value syntax-local-name syntax-local-lift-expression ...

Syntax Parameters define-syntax-parameter syntax-parameterize syntax-parameter-value

Parsing Raw Syntax lexer parser cfg-parser

Inspection raco pkg show

Finding pkgs.racket-lang.org

Installing raco pkg install

Updating raco pkg update

Removing raco pkg remove

Compiling raco make program.rkt

Testing raco test program.rkt a-directory

Building Executables raco exe program.rkt

Extending DrRacket drracket:language:simple-module-based-language->module-based-language-mixin

Slides slide standard-fish code