retroforth/example/LightWeightFlowControl.forth
crc 547bd93747 add some comments and tests to LightWeightFlowControl.forth
FossilOrigin-Name: a9c76be4447552090853990e3e8adf73dabc5850a0349902a962df041ae70e60
2019-03-14 18:37:56 +00:00

33 lines
1,003 B
Forth

These are adapted from HerkForth.
| 0= | n- | exit word if TOS = 0 |
| <; | nn- | exit word if NOS < TOS |
| >; | nn- | exit word if NOS > TOS |
| <>; | nn- | exit word if NOS <> TOS |
| if; | f- | exit word if TOS is TRUE |
| ?; | f- | exit word if TOS is TRUE. Leave Flag on stack if TRUE. |
~~~
:0=; n:zero? [ as{ 'popopodr i 'drdrre.. i }as ] if ;
:<; lt? [ as{ 'popopodr i 'drdrre.. i }as ] if ;
:>; gt? [ as{ 'popopodr i 'drdrre.. i }as ] if ;
:<>; -eq? [ as{ 'popopodr i 'drdrre.. i }as ] if ;
:if; [ as{ 'popopodr i 'drdrre.. i }as ] if ;
:?; dup [ as{ 'popopodr i 'drdrre.. i }as ] if drop ;
~~~
```
:test (n-) n:even? if; 'Odd! s:put nl ;
#1 test
#2 test
```
```
nl '----------------- s:put nl
:test (n-) n:even? ?; 'Odd! s:put nl ;
#1 test dump-stack reset nl
#2 test dump-stack reset nl
```