Schemeroni: Useful Scheme Macaronis

README.md

I will use this Gist to post useful Scheme macros.

These macros will be compliant with R7Rs and down.

All macros are partially tested (warning!). Don't use them in serious work before thorough test.

char-is.scm

; `char-is?` is a hygenic macro that, given a character class and a character, it will tell you if the character belongs to that class.
; This of course only works with ASCII characters.
; Several characters like Tilde are unaccounted for.
; You can use this macro as a basis for your own macro to use in lexers and parsers.

(define (belongs-to? item set)
    (not (eq? (member item set) #f)))

(define-syntax char-is?
  (syntax-rules (newln
                 whitespace
                 blank
                 upper-case
                 lower-case
                 letter
                 numeric
                 delimiter
                 terminator
                 solidus
                 separator
                 apostrophe
                 arithmetic
                 quantifier)
    [(_ newln ch)
     (char=? ch #\newline)]
    [(_ whitespace ch)
     (belongs-to? ch '(#\space #\tab))]
    [(_ blank ch)
     (belongs-to? ch '(#\space #\tab #\newline))]
    [(_ upper-case ch)
     (and (char>=? #\A)
          (char<=? #\Z))]
    [(_ lower-case ch)
     (and (char>=? #\a)
          (char<? #\z))]
    [(_ letter ch)
     (or (and (char>? #\A) (char<? #\Z))
         (and (char>? #\a) (char<? #\z)))]
    [(_ numeric ch)
     (and (char>=? #\0)
          (char<=? #\9))]
    [(_ delimiter ch)
     (belongs-to? ch '(#\( #\) #\[ #\] #\{ #\} #\< #\>))]
    [(_ terminator ch)
     (belongs-to? ch '(#\! #\? #\.))]
    [(_ solidus ch)
     (belongs-to? ch '(#\\ #\/))]
    [(_ separator ch)
     (belongs-to? ch '(#\: #\; #\,))]
    [(_ apostrophe ch)
     (belongs-to? ch '(#\' #\"))]
    [(_ arithmetic ch)
     (belongs-to? ch '(#\+ #\- #\^ #\* #\&))]
    [(_ quantifier ch)
     (belongs-to? ch '(#\@ #\# #\$ #\%))]))