2019-03-26 15:26:06 +01:00
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# Forth to RETRO Cross Reference
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This is a quick overview of some differences between RETRO
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and traditional Forth.
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| Category | Forth | RETRO |
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| ---------------------- | ----------------------- | ----------------------------- |
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| Definitions | `: name ;` | `:name ;` |
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| Numbers | `100 -12` | `#100 #-12` |
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| Characters (interpret) | `CHAR A CHAR D` | `$A $D` |
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| Characters (compile) | `[CHAR] A [CHAR] D` | `$A $D` |
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| Comments | `( This is a comment )` | `(This_is_a_comment)` |
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| Pointers (interpret) | `' Compiler` | `&Compiler` |
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| Pointers (compile) | `['] Compiler | `&Compiler` |
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| Conditionals #1 | `IF 1 THEN` | `[ #1 ] if` |
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| Conditionals #2 | `NOT IF 1 THEN` | `[ #1 ] -if` |
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| Conditionals #3 | `IF 1 ELSE 2 THEN` | `[ #1 ] [ #2 ] choose` |
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| Counted Loops | `10 0 DO LOOP` | `#10 [ ] times` |
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| Counted Loops w/Index | `10 0 DO I LOOP` | `#10 [ I ] times<with-index>` |
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| Unconditional Loops | `BEGIN AGAIN` | `repeat again` |
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| Return Stack | `10 >R ... R>` | `#10 push ... pop` |
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RETRO conditionals and loops can be used outside of definitions, ANS ones can not.
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Some forms are replaced by combinators.
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FORTH
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>R ... R> [ ... ] dip
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DUP >R ... R> [ ... ] sip
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