RETRO provides words for working with ASCII characters.

Sigil

Character constants are returned using the $ sigil.

Namespace

Words operating on characters are in the c: namespace.

Classification

RETRO provides a number of words to determine if a character fits into predefined groups.

The primary words for this are:

c:consonant?
c:digit?
c:letter?
c:lowercase?
c:uppercase?
c:visible?
c:vowel?
c:whitespace?


There are also corresponding "not" forms:

c:-consonant?
c:-digit?
c:-lowercase?
c:-uppercase?
c:-visible?
c:-vowel?
c:-whitespace?


All of these take a character and return either a TRUE or FALSE flag.

Conversions

A few words are provided to convert case. Each takes a character and returns the modified character.

c:to-lower
c:to-number
c:to-upper
c:toggle-case


RETRO also has c:to-string, which takes a character and creates a new temporary string with the character.

I/O

Characters can be displayed using c:put.

```
$a c:put
```


With the default system on BSD, Linux, and macOS (and other Unix style hosts), c:get is provided to read input. This may be buffered, depending on the host.