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.