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fll: more commentary

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crc 2023-01-23 15:44:42 +00:00
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interface/ll.retro
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@ -79,19 +79,32 @@ a pointer to the final cons cell.
}} }}
~~~ ~~~
Appening a value is simple. Create a new cons with the value in
the car and a pointer to END in the cdr. Find the end of the
list, and update the cdr to point to the new cons.
~~~ ~~~
:fll:append/value (pv-) &END cons swap fll:to-end cdr! ; :fll:append/value (pv-) &END cons swap fll:to-end cdr! ;
~~~ ~~~
Given a specific node in the list, follow the cdr chain until
the node number is reached. Starts at zero.
An issue with this: it does not currently check the length to
make sure that the index is valid.
~~~ ~~~
:fll:to-index (pn-p) [ cdr@ ] times ; :fll:to-index (pn-p) [ cdr@ ] times ;
~~~ ~~~
~~~ ~~~
:fll:del :fll:del
dup-pair n:dec fll:to-index [ n:inc fll:to-index ] dip cdr! ; dup-pair n:dec fll:to-index [ n:inc fll:to-index ] dip cdr! ;
~~~ ~~~
The `fll:for-each` runs a quote once for each value in a list.
~~~ ~~~
{{ {{
'Action var 'Action var
@ -102,14 +115,22 @@ a pointer to the final cons cell.
}} }}
~~~ ~~~
To obtain the length of a list (in number of cons) use
`fll:length`.
~~~ ~~~
:fll:length (p-n) #0 swap [ drop n:inc ] fll:for-each n:dec ; :fll:length (p-n) #0 swap [ drop n:inc ] fll:for-each n:dec ;
~~~ ~~~
`fll:drop` removes the a specified cons from a list.
~~~ ~~~
:fll:drop dup fll:length n:dec fll:to-index &END swap cdr! ; :fll:drop dup fll:length n:dec fll:to-index &END swap cdr! ;
~~~ ~~~
`fll:inject` adds a new cons to a list, inserting at a specified
point.
~~~ ~~~
{{ {{
'i var 'i var