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| author | Kaz Kylheku <kaz@kylheku.com> | 2022-01-11 21:14:24 -0800 |
|---|---|---|
| committer | Kaz Kylheku <kaz@kylheku.com> | 2022-01-11 21:14:24 -0800 |
| commit | 2e0f7c370fa5012cb54328eb0e73412cb3c59351 (patch) | |
| tree | 4b7db988ad507f7a42e6be599a5cc601c9dd4260 /stdlib | |
| parent | ef0c40c134bfbef21dc57eadc1b32bc1f08ee670 (diff) | |
| download | txr-2e0f7c370fa5012cb54328eb0e73412cb3c59351.tar.gz txr-2e0f7c370fa5012cb54328eb0e73412cb3c59351.tar.bz2 txr-2e0f7c370fa5012cb54328eb0e73412cb3c59351.zip | |
sum-each, mul-each: handle no vars case.
* stdlib/arith-each.tl (sys:arith-each): If there are no vars,
then just reduce to the identity element value.
This is alreading happening fine for the each-prod family
of operators.
* tests/016/arith.tl: Test cases covering the no vars
and empty iteration identity element cases for sum-each and
mul-each, as well as the *-prod variants.
* txr.1: Document empty iteration and empty vars behavior
for arithmetic each operators as well as the each-prod
family.
Diffstat (limited to 'stdlib')
| -rw-r--r-- | stdlib/arith-each.tl | 22 |
1 files changed, 13 insertions, 9 deletions
diff --git a/stdlib/arith-each.tl b/stdlib/arith-each.tl index 80f783c7..ba8c8c8a 100644 --- a/stdlib/arith-each.tl +++ b/stdlib/arith-each.tl @@ -34,15 +34,19 @@ (defmacro sys:arith-each (:form f op-iv vars . body) (let* ((gens (mapcar (ret (gensym)) vars)) (syms [mapcar car vars]) - (accum (gensym))) - ^(let* (,*(mapcar (ret ^(,@1 (iter-begin ,@2))) gens syms) - (,accum ,(cdr op-iv))) - (block nil - (sys:for-op () - ((and ,*(mapcar (op list 'iter-more) gens)) ,accum) - (,*(mapcar (ret ^(sys:setq ,@1 (iter-step ,@1))) gens)) - ,*(mapcar (ret ^(sys:setq ,@1 (iter-item ,@2))) syms gens) - (set ,accum (,(car op-iv) ,accum (progn ,*body)))))))) + (accum (gensym)) + (op (car op-iv)) + (iv (cdr op-iv))) + (if (null vars) + iv + ^(let* (,*(mapcar (ret ^(,@1 (iter-begin ,@2))) gens syms) + (,accum ,iv)) + (block nil + (sys:for-op () + ((and ,*(mapcar (op list 'iter-more) gens)) ,accum) + (,*(mapcar (ret ^(sys:setq ,@1 (iter-step ,@1))) gens)) + ,*(mapcar (ret ^(sys:setq ,@1 (iter-item ,@2))) syms gens) + (set ,accum (,op ,accum (progn ,*body))))))))) (defmacro sum-each (:form f vars . body) (sys:vars-check f vars) |