Multiple return values of floor in dotimes
The floor Hyperspec article on dotimes has this example:
(defun palindromep (string &optional
(start 0)
(end (length string)))
(dotimes (k (floor (- end start) 2) t)
(unless (char-equal (char string (+ start k))
(char string (- end k 1)))
(return nil))))
If floor returns two values, e.g. (floor 5 2) -> 2 and 1, how does dotimes know to just use the first value and disregard the second for its count-form?
common-lisp floor multiple-value
edited Nov 23 '18 at 9:34
coredump
21.3k33046
asked Nov 22 '18 at 18:41
147pm147pm
582416
add a comment |
The floor Hyperspec article on dotimes has this example:
(defun palindromep (string &optional
(start 0)
(end (length string)))
(dotimes (k (floor (- end start) 2) t)
(unless (char-equal (char string (+ start k))
(char string (- end k 1)))
(return nil))))
If floor returns two values, e.g. (floor 5 2) -> 2 and 1, how does dotimes know to just use the first value and disregard the second for its count-form?
common-lisp floor multiple-value
edited Nov 23 '18 at 9:34
coredump
21.3k33046
asked Nov 22 '18 at 18:41
147pm147pm
582416
add a comment |
The floor Hyperspec article on dotimes has this example:
(defun palindromep (string &optional
(start 0)
(end (length string)))
(dotimes (k (floor (- end start) 2) t)
(unless (char-equal (char string (+ start k))
(char string (- end k 1)))
(return nil))))
If floor returns two values, e.g. (floor 5 2) -> 2 and 1, how does dotimes know to just use the first value and disregard the second for its count-form?
common-lisp floor multiple-value
edited Nov 23 '18 at 9:34
coredump
21.3k33046
asked Nov 22 '18 at 18:41
147pm147pm
582416
The floor Hyperspec article on dotimes has this example:
(defun palindromep (string &optional
(start 0)
(end (length string)))
(dotimes (k (floor (- end start) 2) t)
(unless (char-equal (char string (+ start k))
(char string (- end k 1)))
(return nil))))
If floor returns two values, e.g. (floor 5 2) -> 2 and 1, how does dotimes know to just use the first value and disregard the second for its count-form?
common-lisp floor multiple-value
common-lisp floor multiple-value
edited Nov 23 '18 at 9:34
coredump
21.3k33046
asked Nov 22 '18 at 18:41
147pm147pm
582416
edited Nov 23 '18 at 9:34
coredump
21.3k33046
asked Nov 22 '18 at 18:41
147pm147pm
582416
edited Nov 23 '18 at 9:34
coredump
21.3k33046
edited Nov 23 '18 at 9:34
coredump
21.3k33046
edited Nov 23 '18 at 9:34
coredump
21.3k33046
21.3k33046
asked Nov 22 '18 at 18:41
147pm147pm
582416
asked Nov 22 '18 at 18:41
147pm147pm
582416
asked Nov 22 '18 at 18:41
147pm147pm
582416
582416
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
From 7.10.1,
Normally multiple values are not used. Special forms are required both to produce multiple values and to receive them. If the caller of a function does not request multiple values, but the called function produces multiple values, then the first value is given to the caller and all others are discarded; if the called function produces zero values, then the caller gets
nilas a value.
Unless you specifically do something to deal with the multiple values (such as by multiple-value-call or one of the various macros equipped to handle them), all except the first value will be ignored.
answered Nov 22 '18 at 18:48
Silvio MayoloSilvio Mayolo
14.1k22453
add a comment |
It's a general mechanism and not specific to dotimes.
If one calls a function or sets a variable, then only the first value will be passed:
CL-USER 52 > (defun foo (x) x)
FOO
CL-USER 53 > (foo (floor 5 2))
2
CL-USER 54 > (let ((foo (floor 5 2)))
foo)
2
To do the equivalent (calling functions, binding variables) with multiple values, one needs to use special constructs:
CL-USER 55 > (multiple-value-call #'list
(floor 5 2) (floor 7 3))
(2 1 2 1)
CL-USER 56 > (multiple-value-bind (foo0 foo1)
(floor 5 2)
(list foo0 foo1))
(2 1)
answered Nov 22 '18 at 19:21
Rainer JoswigRainer Joswig
111k8166283
Is this an example of functional's basic lambda calculus need/tendency to curry?
– 147pm
Nov 22 '18 at 21:11
@147pm: no, that's unrelated
– Rainer Joswig
Nov 22 '18 at 21:16
add a comment |
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2 Answers
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2 Answers
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oldest
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From 7.10.1,
Normally multiple values are not used. Special forms are required both to produce multiple values and to receive them. If the caller of a function does not request multiple values, but the called function produces multiple values, then the first value is given to the caller and all others are discarded; if the called function produces zero values, then the caller gets
nilas a value.
Unless you specifically do something to deal with the multiple values (such as by multiple-value-call or one of the various macros equipped to handle them), all except the first value will be ignored.
answered Nov 22 '18 at 18:48
Silvio MayoloSilvio Mayolo
14.1k22453
add a comment |
From 7.10.1,
Normally multiple values are not used. Special forms are required both to produce multiple values and to receive them. If the caller of a function does not request multiple values, but the called function produces multiple values, then the first value is given to the caller and all others are discarded; if the called function produces zero values, then the caller gets
nilas a value.
Unless you specifically do something to deal with the multiple values (such as by multiple-value-call or one of the various macros equipped to handle them), all except the first value will be ignored.
answered Nov 22 '18 at 18:48
Silvio MayoloSilvio Mayolo
14.1k22453
add a comment |
From 7.10.1,
Normally multiple values are not used. Special forms are required both to produce multiple values and to receive them. If the caller of a function does not request multiple values, but the called function produces multiple values, then the first value is given to the caller and all others are discarded; if the called function produces zero values, then the caller gets
nilas a value.
Unless you specifically do something to deal with the multiple values (such as by multiple-value-call or one of the various macros equipped to handle them), all except the first value will be ignored.
answered Nov 22 '18 at 18:48
Silvio MayoloSilvio Mayolo
14.1k22453
From 7.10.1,
Normally multiple values are not used. Special forms are required both to produce multiple values and to receive them. If the caller of a function does not request multiple values, but the called function produces multiple values, then the first value is given to the caller and all others are discarded; if the called function produces zero values, then the caller gets
nilas a value.
Unless you specifically do something to deal with the multiple values (such as by multiple-value-call or one of the various macros equipped to handle them), all except the first value will be ignored.
answered Nov 22 '18 at 18:48
Silvio MayoloSilvio Mayolo
14.1k22453
answered Nov 22 '18 at 18:48
Silvio MayoloSilvio Mayolo
14.1k22453
answered Nov 22 '18 at 18:48
Silvio MayoloSilvio Mayolo
14.1k22453
answered Nov 22 '18 at 18:48
Silvio MayoloSilvio Mayolo
14.1k22453
14.1k22453
add a comment |
add a comment |
It's a general mechanism and not specific to dotimes.
If one calls a function or sets a variable, then only the first value will be passed:
CL-USER 52 > (defun foo (x) x)
FOO
CL-USER 53 > (foo (floor 5 2))
2
CL-USER 54 > (let ((foo (floor 5 2)))
foo)
2
To do the equivalent (calling functions, binding variables) with multiple values, one needs to use special constructs:
CL-USER 55 > (multiple-value-call #'list
(floor 5 2) (floor 7 3))
(2 1 2 1)
CL-USER 56 > (multiple-value-bind (foo0 foo1)
(floor 5 2)
(list foo0 foo1))
(2 1)
answered Nov 22 '18 at 19:21
Rainer JoswigRainer Joswig
111k8166283
Is this an example of functional's basic lambda calculus need/tendency to curry?
– 147pm
Nov 22 '18 at 21:11
@147pm: no, that's unrelated
– Rainer Joswig
Nov 22 '18 at 21:16
add a comment |
It's a general mechanism and not specific to dotimes.
If one calls a function or sets a variable, then only the first value will be passed:
CL-USER 52 > (defun foo (x) x)
FOO
CL-USER 53 > (foo (floor 5 2))
2
CL-USER 54 > (let ((foo (floor 5 2)))
foo)
2
To do the equivalent (calling functions, binding variables) with multiple values, one needs to use special constructs:
CL-USER 55 > (multiple-value-call #'list
(floor 5 2) (floor 7 3))
(2 1 2 1)
CL-USER 56 > (multiple-value-bind (foo0 foo1)
(floor 5 2)
(list foo0 foo1))
(2 1)
answered Nov 22 '18 at 19:21
Rainer JoswigRainer Joswig
111k8166283
Is this an example of functional's basic lambda calculus need/tendency to curry?
– 147pm
Nov 22 '18 at 21:11
@147pm: no, that's unrelated
– Rainer Joswig
Nov 22 '18 at 21:16
add a comment |
It's a general mechanism and not specific to dotimes.
If one calls a function or sets a variable, then only the first value will be passed:
CL-USER 52 > (defun foo (x) x)
FOO
CL-USER 53 > (foo (floor 5 2))
2
CL-USER 54 > (let ((foo (floor 5 2)))
foo)
2
To do the equivalent (calling functions, binding variables) with multiple values, one needs to use special constructs:
CL-USER 55 > (multiple-value-call #'list
(floor 5 2) (floor 7 3))
(2 1 2 1)
CL-USER 56 > (multiple-value-bind (foo0 foo1)
(floor 5 2)
(list foo0 foo1))
(2 1)
answered Nov 22 '18 at 19:21
Rainer JoswigRainer Joswig
111k8166283
It's a general mechanism and not specific to dotimes.
If one calls a function or sets a variable, then only the first value will be passed:
CL-USER 52 > (defun foo (x) x)
FOO
CL-USER 53 > (foo (floor 5 2))
2
CL-USER 54 > (let ((foo (floor 5 2)))
foo)
2
To do the equivalent (calling functions, binding variables) with multiple values, one needs to use special constructs:
CL-USER 55 > (multiple-value-call #'list
(floor 5 2) (floor 7 3))
(2 1 2 1)
CL-USER 56 > (multiple-value-bind (foo0 foo1)
(floor 5 2)
(list foo0 foo1))
(2 1)
answered Nov 22 '18 at 19:21
Rainer JoswigRainer Joswig
111k8166283
edited Nov 23 '18 at 11:27
answered Nov 22 '18 at 19:21
Rainer JoswigRainer Joswig
111k8166283
answered Nov 22 '18 at 19:21
Rainer JoswigRainer Joswig
111k8166283
answered Nov 22 '18 at 19:21
Rainer JoswigRainer Joswig
111k8166283
111k8166283
Is this an example of functional's basic lambda calculus need/tendency to curry?
– 147pm
Nov 22 '18 at 21:11
@147pm: no, that's unrelated
– Rainer Joswig
Nov 22 '18 at 21:16
add a comment |
Is this an example of functional's basic lambda calculus need/tendency to curry?
– 147pm
Nov 22 '18 at 21:11
@147pm: no, that's unrelated
– Rainer Joswig
Nov 22 '18 at 21:16
Is this an example of functional's basic lambda calculus need/tendency to curry?
– 147pm
Nov 22 '18 at 21:11
Is this an example of functional's basic lambda calculus need/tendency to curry?
– 147pm
Nov 22 '18 at 21:11
@147pm: no, that's unrelated
– Rainer Joswig
Nov 22 '18 at 21:16
@147pm: no, that's unrelated
– Rainer Joswig
Nov 22 '18 at 21:16
add a comment |
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