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# Forth to RETRO Cross Reference
This is a quick overview of some differences between RETRO
and traditional Forth.
| Category | Forth | RETRO |
| ---------------------- | ----------------------- | ----------------------------- |
| Definitions | `: name ;` | `:name ;` |
| Numbers | `100 -12` | `#100 #-12` |
| Characters (interpret) | `CHAR A CHAR D` | `$A $D` |
| Characters (compile) | `[CHAR] A [CHAR] D` | `$A $D` |
| Comments | `( This is a comment )` | `(This_is_a_comment)` |
| Pointers (interpret) | `' Compiler` | `&Compiler` |
| Pointers (compile) | `['] Compiler | `&Compiler` |
| Conditionals #1 | `IF 1 THEN` | `[ #1 ] if` |
| Conditionals #2 | `NOT IF 1 THEN` | `[ #1 ] -if` |
| Conditionals #3 | `IF 1 ELSE 2 THEN` | `[ #1 ] [ #2 ] choose` |
| Counted Loops | `10 0 DO LOOP` | `#10 [ ] times` |
| Counted Loops w/Index | `10 0 DO I LOOP` | `#10 [ I ] indexed-times` |
| Unconditional Loops | `BEGIN AGAIN` | `repeat again` |
| Return Stack | `10 >R ... R>` | `#10 push ... pop` |
RETRO conditionals and loops can be used outside of definitions, ANS ones can not.
Some forms are replaced by combinators.
FORTH
>R ... R> [ ... ] dip
DUP >R ... R> [ ... ] sip