dyoo

#lang typed/racket

(define-type T (U String Integer))

(: fizzbuzz/1 : (Integer -> T))
(define (fizzbuzz/1 x)
  (define mod3 (zero? (modulo x 3)))
  (define mod5 (zero? (modulo x 5)))
  (cond [(and mod3 mod5) "fizzbuzz"]
        [mod3 "fizz"]

dyoo

#lang racket

(require syntax/modresolve)

;; An example of letting Racket tell you where things are defined.
(resolve-module-path-index (first (identifier-binding #'for/hash))
                           (current-directory))

dyoo

#lang racket
            
(define-syntax (for/string stx)
  (syntax-case stx ()
    [(_ clauses . defs+exprs)
     (with-syntax ([original stx])
       (syntax/loc stx
         (apply string-append
                (reverse
                 (for/fold/derived original

dyoo

#lang racket


(define (find-duplicates elts)
  (define ht (make-hash))
  (for/fold ([dups '()]) ([x (in-list elts)])
    (hash-set! ht x (add1 (hash-ref ht x 0)))
    (cond
      [(= (hash-ref ht x) 2)
       (cons x dups)]

dyoo

#lang racket


;; A str-expr is either:
;;
;;     1.  a plain string, or
;;     2.  (list '+ str-expr str-expr)
;;     3.  (list '* number str-expr)

;; evaluate: str-expr -> string

dyoo

#lang racket

(define (f x)
  (* x x))
(provide f)


(module* foo racket/base
  ;; External test of the function
  (require rackunit

dyoo

#lang racket



(module foo ragg/sexp/lang
  rule-1: "0"+ || rule-2
  rule-2: "1"
  )

(require (prefix-in test: (submod "." foo)))

dyoo

#lang racket/base
 
(require (for-syntax racket/base syntax/parse))
(module+ test (require rackunit))
 
(define-syntax (test+ stx)
  (syntax-parse stx
    #:literals (=>)
    [(_ (fn arg ...) => v)
     (with-syntax ([fn-name (symbol->string (syntax->datum #'fn))])

dyoo

#lang racket
(require syntax/parse)

(syntax-parse #'("foo" "bar")
  [((~and "foo" x) y)
   (list #'x #'y)])
   
(syntax-parse #'("food" "bar")
  [((~and "foo" x) y)
   (list #'x #'y)])

dyoo

#lang racket/base

(require ragg/examples/simple-line-drawing/lexer
         ragg/examples/simple-line-drawing/grammar
         syntax/strip-context
         syntax/parse
         (for-syntax racket/base))


(define-syntax (drawing stx) (raise-syntax-error #f "Don't look at me; I'm shy" stx))