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Diffstat (limited to 'src/interp/sys-utility.boot')
| -rw-r--r-- | src/interp/sys-utility.boot | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/src/interp/sys-utility.boot b/src/interp/sys-utility.boot index d047296e..6895926e 100644 --- a/src/interp/sys-utility.boot +++ b/src/interp/sys-utility.boot @@ -391,3 +391,25 @@ stringAssoc(s,l) == symbolLassoc(s,l) == p := symbolAssoc(s,l) => rest p nil + + +--% substitute + +substitute(new,old,tree) == + sameObject?(old,tree) => new + cons? tree => + h := substitute(new,old,first tree) + t := substitute(new,old,rest tree) + sameObject?(h,first tree) and sameObject?(t,rest tree) => tree + [h,:t] + tree + +substitute!(new,old,tree) == + sameObject?(old,tree) => new + cons? tree => + h := substitute!(new,old,first tree) + t := substitute!(new,old,rest tree) + tree.first := h + tree.rest := t + tree + |