Re: [Chicken-users] Using epsilon in test egg
On Mon, Jul 28, 2014 at 09:46:57PM +0900, Alex Shinn wrote: Regardless, I'll add a utility to make defining tests with your own comparator easier, and explicitly export test-approx-equal? so you don't have to capture the initial test comparator. While you're looking at that, could you also take a look at this ticket? https://bugs.call-cc.org/ticket/935 Thanks! Cheers, Peter -- http://www.more-magic.net ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Using epsilon in test egg
Peter Bex scripsit: While you're looking at that, could you also take a look at this ticket? https://bugs.call-cc.org/ticket/935 In addition, the page on comparing floats that you pointed to now has a replacement: http://randomascii.wordpress.com/2012/02/25/comparing-floating-point-numbers-2012-edition/. -- John Cowan http://www.ccil.org/~cowanco...@ccil.org After fixing the Y2K bug in an application: WELCOME TO censored DATE: MONDAK, JANUARK 1, 1900 ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Using epsilon in test egg
On Wed, Jul 30, 2014 at 9:33 PM, John Cowan co...@mercury.ccil.org wrote: Peter Bex scripsit: While you're looking at that, could you also take a look at this ticket? https://bugs.call-cc.org/ticket/935 That was from 22 months ago... I don't remember exactly when it was fixed but it works now. Closed the bug. In addition, the page on comparing floats that you pointed to now has a replacement: http://randomascii.wordpress.com/2012/02/25/comparing-floating-point-numbers-2012-edition/ . Heh, I was actually reading that page, linked from the previous page, but it gets put inside a frame so copying the location failed... -- Alex ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Using epsilon in test egg
On Wed, Jul 30, 2014 at 10:00:00PM +0900, Alex Shinn wrote: On Wed, Jul 30, 2014 at 9:33 PM, John Cowan co...@mercury.ccil.org wrote: Peter Bex scripsit: While you're looking at that, could you also take a look at this ticket? https://bugs.call-cc.org/ticket/935 That was from 22 months ago... Yeah, I just happened to stumble across it while performing maintenance duties on the bugtracker, and saw this thread. I don't remember exactly when it was fixed but it works now. Closed the bug. Thanks! A maintained bugtracker is a useful bugtracker :) Cheers, Peter -- http://www.more-magic.net ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Using epsilon in test egg
On 29/07/14 04:58, Alex Shinn wrote: On Mon, Jul 28, 2014 at 10:09 PM, John Cowan co...@mercury.ccil.org mailto:co...@mercury.ccil.org wrote: Alex Shinn scripsit: If people think it's useful I'd consider walking pairs and vectors. They are the most important cases, because the expected value is expressed as a literal value, and that can only be a list or vector. Actually, the expected value can be anything. Literals may be the more common case though. As an interesting case in point, I have written a bunch of tests for procedures that have side-effects (where all I'm testing is that they don't raise any conditions or whatever) of the form: (test Do foo (void) (do-foo! ...)) ...which works, because I make sure I return (void) rather than some arbitrary expression from my side-effecting procedures! I've also thrown together a few macros for a common case - I have a constructor that makes an (opaque) object, and I want to test that the construction doesn't raise conditions, while keeping the value for later use. I do it with: (define-syntax test-define (syntax-rules () ((_ var expr) (test-define (-string '(define var expr)) var expr)) ((_ name var expr) (begin (define var (void)) (test-no-errors name (set! var expr)) (define-syntax test-define-values (syntax-rules () ((_ (var ...) expr) (test-define-values (-string '(define-values (var ...) expr)) (var ...) expr)) ((_ name (var ...) expr) (begin (define var (void)) ... (test-no-errors name (set!-values (var ...) expr)) Then I can do the likes of: (test-define Create key-stream writer ksw (make-key-stream-writer* a 'test-ks)) (test-define-values Close key-stream writer (ks-hash ks-reused?) ((key-stream-writer-finish! ksw))) ABS -- Alaric Snell-Pym http://www.snell-pym.org.uk/alaric/ ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Using epsilon in test egg
Alex Shinn scripsit: The solution is definitely not to write your own comparison function, and trust that the test egg is doing the right thing. It isn't, though, not quite. What it needs to do is not a dichotomy of if inexact, use epsilon, otherwise use `equal?` but rather to have a version of `equal?` that uses epsilon when it comes to a float. That way comparisons against list or vector structure that contains floats (as in the OP's case) will work correctly. -- John Cowan http://www.ccil.org/~cowanco...@ccil.org What has four pairs of pants, lives in Philadelphia, and it never rains but it pours? --Rufus T. Firefly ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Using epsilon in test egg
On Mon, Jul 28, 2014 at 9:30 PM, John Cowan co...@mercury.ccil.org wrote: Alex Shinn scripsit: The solution is definitely not to write your own comparison function, and trust that the test egg is doing the right thing. It isn't, though, not quite. What it needs to do is not a dichotomy of if inexact, use epsilon, otherwise use `equal?` but rather to have a version of `equal?` that uses epsilon when it comes to a float. That way comparisons against list or vector structure that contains floats (as in the OP's case) will work correctly. I meant the right thing wrt comparing two inexacts, as opposed to trying to come up with your own inexact=? logic. It's easy to make it handle nested pairs and vectors correctly, would require lolevel hackery to handle records, and in general can't support ffi struct types. So at some point you need to provide your own structure comparison, and I chose to make the rule simple: If you explicitly expect a single inexact value, assume the result should also be inexact and approximately equal. Otherwise use equal?. If people think it's useful I'd consider walking pairs and vectors. Regardless, I'll add a utility to make defining tests with your own comparator easier, and explicitly export test-approx-equal? so you don't have to capture the initial test comparator. -- Alex ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Using epsilon in test egg
Alex Shinn scripsit: If people think it's useful I'd consider walking pairs and vectors. They are the most important cases, because the expected value is expressed as a literal value, and that can only be a list or vector. If you are using `test-assert`, you can specify your own function directly. Regardless, I'll add a utility to make defining tests with your own comparator easier, and explicitly export test-approx-equal? so you don't have to capture the initial test comparator. +1 -- John Cowan http://www.ccil.org/~cowanco...@ccil.org La mayyitan ma qadirun yatabaqqa sarmadi Fa idha yaji' al-shudhdhadh fa-l-maut qad yantahi. --Abdullah al-Hazred, Al-`Azif ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Using epsilon in test egg
On Mon, Jul 28, 2014 at 10:09 PM, John Cowan co...@mercury.ccil.org wrote: Alex Shinn scripsit: If people think it's useful I'd consider walking pairs and vectors. They are the most important cases, because the expected value is expressed as a literal value, and that can only be a list or vector. Actually, the expected value can be anything. Literals may be the more common case though. -- Alex ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Using epsilon in test egg
On Sun, Jul 27, 2014 at 10:03 AM, Matt Gushee m...@gushee.net wrote: Hmm, just realized something. The test egg documentation also says: Percentage difference allowed ... So if the expected value is 0, then no variance is allowed? If that's true, then epsilon isn't what I want anyway. I need to allow an absolute amount of variance that is independent of the values being tested. By the way, in general you do _not_ want absolute differences. The test egg is doing the right thing for general comparisons. Arguably it may be better to use ULPs (Units in the Last Place), but they're harder to get at in portable Scheme and not clearly better. For more than you ever wanted to know about the subject see: http://www.cygnus-software.com/papers/comparingfloats/comparingfloats.htm The solution is definitely not to write your own comparison function, and trust that the test egg is doing the right thing. -- Alex Anyway, I'd appreciate help in understanding how this is supposed to work ... On Sat, Jul 26, 2014 at 6:42 PM, Matt Gushee m...@gushee.net wrote: Hi, folks-- I am working on an application that does a lot of floating-point calculations, and I'm having trouble with the test suite. The program is based on the imlib2 egg, and it does some fairly simple image processing for web applications, so the numbers in question are RGBA color values. Internally I am handling all the numbers as floats in the range 0-1, because the blending and compositing formulas are much more straightforward that way compared to using integers 0-255. So I have a number of functions that produce lists of numbers like these: '(0.323 0.788834 0.12 0.4) '(0 0 0 1.0) '(0.67 0.4 0.562 0.0) And given the above, a moderate degree of imprecision in the results is perfectly acceptable - I haven't yet confirmed this with actual images, but I'm thinking as much as 0.5% variance should work fine (basically, as long as the colors in the generated images look as expected to a casual observer, the result should be acceptable). So of course I want the test results to reflect this. I am using the following procedure to compare number lists: (define (list= l1 l2) (and (= (length l1) (length l2)) (let loop ((l1* l1) (l2* l2)) (cond ((null? l1*) #t) ((= (car l1*) (car l2*)) (loop (cdr l1*) (cdr l2*))) (else #f) And for the tests that use this predicate, I set (current-test-epsilon 0.005) [or 0.002 or 0.001 - it doesn't seem to make any difference] But I'm finding that certain tests still fail unexpectedly, e.g. 2.03.10: (parse-color 167,215,51 #f) = '(0.655 0.843 0.200 1.0) [ FAIL] expected (0.655 0.843 0.2 1.0) but got (0.654901960784314 0.843137254901961 0.2 1.0) But: (/ 0.654901960784314 0.655) = 0.999850321808113 (/ 0.843137254901961 0.843) = 1.0001628172028 So it would appear that the epsilon value does not apply to these tests. I can certainly define a custom equality predicate that will do what I need, but this is bugging me. I guess I don't really understand how epsilon is supposed to work. The test egg documentation says that applies to 'inexact comparisons', but I can't find a definition of 'inexact comparison'. I have also read that '=' may be unreliable for inexact numbers, but I don't know what else to use. Perhaps 'fp=' from the Chicken library? Then I would have to ensure that all numbers are expressed as floats, whereas currently my code has a number of cases where 1 and 0 are expressed as integers. So ... do I understand the problem correctly? Any recommendations? Matt Gushee ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
[Chicken-users] Using epsilon in test egg
Hi, folks-- I am working on an application that does a lot of floating-point calculations, and I'm having trouble with the test suite. The program is based on the imlib2 egg, and it does some fairly simple image processing for web applications, so the numbers in question are RGBA color values. Internally I am handling all the numbers as floats in the range 0-1, because the blending and compositing formulas are much more straightforward that way compared to using integers 0-255. So I have a number of functions that produce lists of numbers like these: '(0.323 0.788834 0.12 0.4) '(0 0 0 1.0) '(0.67 0.4 0.562 0.0) And given the above, a moderate degree of imprecision in the results is perfectly acceptable - I haven't yet confirmed this with actual images, but I'm thinking as much as 0.5% variance should work fine (basically, as long as the colors in the generated images look as expected to a casual observer, the result should be acceptable). So of course I want the test results to reflect this. I am using the following procedure to compare number lists: (define (list= l1 l2) (and (= (length l1) (length l2)) (let loop ((l1* l1) (l2* l2)) (cond ((null? l1*) #t) ((= (car l1*) (car l2*)) (loop (cdr l1*) (cdr l2*))) (else #f) And for the tests that use this predicate, I set (current-test-epsilon 0.005) [or 0.002 or 0.001 - it doesn't seem to make any difference] But I'm finding that certain tests still fail unexpectedly, e.g. 2.03.10: (parse-color 167,215,51 #f) = '(0.655 0.843 0.200 1.0) [ FAIL] expected (0.655 0.843 0.2 1.0) but got (0.654901960784314 0.843137254901961 0.2 1.0) But: (/ 0.654901960784314 0.655) = 0.999850321808113 (/ 0.843137254901961 0.843) = 1.0001628172028 So it would appear that the epsilon value does not apply to these tests. I can certainly define a custom equality predicate that will do what I need, but this is bugging me. I guess I don't really understand how epsilon is supposed to work. The test egg documentation says that applies to 'inexact comparisons', but I can't find a definition of 'inexact comparison'. I have also read that '=' may be unreliable for inexact numbers, but I don't know what else to use. Perhaps 'fp=' from the Chicken library? Then I would have to ensure that all numbers are expressed as floats, whereas currently my code has a number of cases where 1 and 0 are expressed as integers. So ... do I understand the problem correctly? Any recommendations? Matt Gushee ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Using epsilon in test egg
On 27/07/14 01:42, Matt Gushee wrote: I can certainly define a custom equality predicate that will do what I need, but this is bugging me. I guess I don't really understand how epsilon is supposed to work. The test egg documentation says that applies to 'inexact comparisons', but I can't find a definition of 'inexact comparison'. I have also read that '=' may be unreliable for inexact numbers, but I don't know what else to use. Perhaps 'fp=' from the Chicken library? Then I would have to ensure that all numbers are expressed as floats, whereas currently my code has a number of cases where 1 and 0 are expressed as integers. As I understand it, the test egg epsilon won't change the behaviour of = - it's used purely internally by the test egg when you say the likes of: (test 1.0 (+ 0.5 0.5)) It's probably best to define your own equality predicate, I think! ABS -- Alaric Snell-Pym http://www.snell-pym.org.uk/alaric/ signature.asc Description: OpenPGP digital signature ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Using epsilon in test egg
Hmm, just realized something. The test egg documentation also says: Percentage difference allowed ... So if the expected value is 0, then no variance is allowed? If that's true, then epsilon isn't what I want anyway. I need to allow an absolute amount of variance that is independent of the values being tested. Anyway, I'd appreciate help in understanding how this is supposed to work ... On Sat, Jul 26, 2014 at 6:42 PM, Matt Gushee m...@gushee.net wrote: Hi, folks-- I am working on an application that does a lot of floating-point calculations, and I'm having trouble with the test suite. The program is based on the imlib2 egg, and it does some fairly simple image processing for web applications, so the numbers in question are RGBA color values. Internally I am handling all the numbers as floats in the range 0-1, because the blending and compositing formulas are much more straightforward that way compared to using integers 0-255. So I have a number of functions that produce lists of numbers like these: '(0.323 0.788834 0.12 0.4) '(0 0 0 1.0) '(0.67 0.4 0.562 0.0) And given the above, a moderate degree of imprecision in the results is perfectly acceptable - I haven't yet confirmed this with actual images, but I'm thinking as much as 0.5% variance should work fine (basically, as long as the colors in the generated images look as expected to a casual observer, the result should be acceptable). So of course I want the test results to reflect this. I am using the following procedure to compare number lists: (define (list= l1 l2) (and (= (length l1) (length l2)) (let loop ((l1* l1) (l2* l2)) (cond ((null? l1*) #t) ((= (car l1*) (car l2*)) (loop (cdr l1*) (cdr l2*))) (else #f) And for the tests that use this predicate, I set (current-test-epsilon 0.005) [or 0.002 or 0.001 - it doesn't seem to make any difference] But I'm finding that certain tests still fail unexpectedly, e.g. 2.03.10: (parse-color 167,215,51 #f) = '(0.655 0.843 0.200 1.0) [ FAIL] expected (0.655 0.843 0.2 1.0) but got (0.654901960784314 0.843137254901961 0.2 1.0) But: (/ 0.654901960784314 0.655) = 0.999850321808113 (/ 0.843137254901961 0.843) = 1.0001628172028 So it would appear that the epsilon value does not apply to these tests. I can certainly define a custom equality predicate that will do what I need, but this is bugging me. I guess I don't really understand how epsilon is supposed to work. The test egg documentation says that applies to 'inexact comparisons', but I can't find a definition of 'inexact comparison'. I have also read that '=' may be unreliable for inexact numbers, but I don't know what else to use. Perhaps 'fp=' from the Chicken library? Then I would have to ensure that all numbers are expressed as floats, whereas currently my code has a number of cases where 1 and 0 are expressed as integers. So ... do I understand the problem correctly? Any recommendations? Matt Gushee ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Using epsilon in test egg
Hi Matt, The problem you’re having is because test only uses the approximate comparison (using current-test-epsilon) when the _expected_ value is inexact: http://api.call-cc.org/doc/scheme/inexact%3F Since your expected value is a list (i.e. inexact? will result in #f given a list), test is testing using equal? which, as you noted, will likely fail for floating point values. All you’ll need to do to properly test your lists is to break the test down so that you are testing the floats one at a time. You could also set current-test-comparator to a function that will work given your requirements. This is the default current-test-comparator: (define (test-equal? expect res) (or (equal? expect res) (and (number? expect) (inexact? expect) (inexact? res) (approx-equal? expect res (current-test-epsilon) You could change it to something like: (define (rgb-test-equal? expect res) (or (equal? expect res) (and (rgb? expect) (rgb-equal? expect res)) (and (number? expect) (inexact? expect) (inexact? res) (approx-equal? expect res (current-test-epsilon) With appropriate definitions for rgb? and rgb-equal? Matt Gushee writes: Hi, folks-- I am working on an application that does a lot of floating-point calculations, and I'm having trouble with the test suite. The program is based on the imlib2 egg, and it does some fairly simple image processing for web applications, so the numbers in question are RGBA color values. Internally I am handling all the numbers as floats in the range 0-1, because the blending and compositing formulas are much more straightforward that way compared to using integers 0-255. So I have a number of functions that produce lists of numbers like these: '(0.323 0.788834 0.12 0.4) '(0 0 0 1.0) '(0.67 0.4 0.562 0.0) And given the above, a moderate degree of imprecision in the results is perfectly acceptable - I haven't yet confirmed this with actual images, but I'm thinking as much as 0.5% variance should work fine (basically, as long as the colors in the generated images look as expected to a casual observer, the result should be acceptable). So of course I want the test results to reflect this. I am using the following procedure to compare number lists: (define (list= l1 l2) (and (= (length l1) (length l2)) (let loop ((l1* l1) (l2* l2)) (cond ((null? l1*) #t) ((= (car l1*) (car l2*)) (loop (cdr l1*) (cdr l2*))) (else #f) And for the tests that use this predicate, I set (current-test-epsilon 0.005) [or 0.002 or 0.001 - it doesn't seem to make any difference] But I'm finding that certain tests still fail unexpectedly, e.g. 2.03.10: (parse-color 167,215,51 #f) = '(0.655 0.843 0.200 1.0) [ FAIL] expected (0.655 0.843 0.2 1.0) but got (0.654901960784314 0.843137254901961 0.2 1.0) But: (/ 0.654901960784314 0.655) = 0.999850321808113 (/ 0.843137254901961 0.843) = 1.0001628172028 So it would appear that the epsilon value does not apply to these tests. I can certainly define a custom equality predicate that will do what I need, but this is bugging me. I guess I don't really understand how epsilon is supposed to work. The test egg documentation says that applies to 'inexact comparisons', but I can't find a definition of 'inexact comparison'. I have also read that '=' may be unreliable for inexact numbers, but I don't know what else to use. Perhaps 'fp=' from the Chicken library? Then I would have to ensure that all numbers are expressed as floats, whereas currently my code has a number of cases where 1 and 0 are expressed as integers. So ... do I understand the problem correctly? Any recommendations? Matt Gushee ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users -- Alex ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Using epsilon in test egg
On Sat, Jul 26, 2014 at 6:57 PM, Alaric Snell-Pym ala...@snell-pym.org.uk wrote: It's probably best to define your own equality predicate, I think! Yes, I think you're right. Thanks! ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Using epsilon in test egg
Hi, John-- On Sat, Jul 26, 2014 at 7:47 PM, John Cowan co...@mercury.ccil.org wrote: Matt Gushee scripsit: Other posters have addressed the main issues, but I'll just point out that inexact comparison means comparison for equality of inexact numbers. Epsilon is applied only by the default predicate: it's assumed that if you write your own equality predicate, you know what you want. I was coming to that conclusion myself, but it's good to have an authoritative answer. = also works correctly for all floats. It's computation itself that isn't always mathematically correct, Indeed. I know that much, at least. Though I can still remember the time (around 2001?) when I saw that a calculation that was supposed to produce 1 actually produced 0.962734 or something like that, and I went WTFFF? Thanks. -- Matt ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Using epsilon in test egg
Matt Gushee writes: I guess my explanation wasn't entirely clear, but that's pretty much what I was already doing. I showed the equality predicate I was using, which tests individual values in the list with = . I think my mistake was in assuming that (current-test-epsilon) would apply to = in the test environment. I'm guessing now that that is not the case. Ah, yes, I hadn’t understood how you were testing. You’re right that = does not get redefined to use current-test-epsilon. Instead you would have to use your own equality predicate that incorporates it. test defines its approx-equal? as: (define (approx-equal? a b epsilon) (cond (( (abs a) (abs b)) (approx-equal? b a epsilon)) ((zero? b) ( (abs a) epsilon)) (else ( (abs (/ (- a b) b)) epsilon Which you could then add to your predicate like so: (define (list= l1 l2) (and (= (length l1) (length l2)) (let loop ((l1* l1) (l2* l2)) (cond ((null? l1*) #t) ((approx-equal? (car l1*) (car l2*) (current-test-epsilon)) (loop (cdr l1*) (cdr l2*))) (else #f) -- Alex ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Using epsilon in test egg
On Sun, Jul 27, 2014 at 10:03 AM, Matt Gushee m...@gushee.net wrote: Hmm, just realized something. The test egg documentation also says: Percentage difference allowed ... So if the expected value is 0, then no variance is allowed? Naturally we handle this case correctly and check the absolute difference in one value is zero. I've added a clarification to the docs. -- Alex ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] Using epsilon in test egg
On Sun, Jul 27, 2014 at 11:02 AM, Alex Charlton alex.n.charl...@gmail.com wrote: Matt Gushee writes: I guess my explanation wasn't entirely clear, but that's pretty much what I was already doing. I showed the equality predicate I was using, which tests individual values in the list with = . I think my mistake was in assuming that (current-test-epsilon) would apply to = in the test environment. I'm guessing now that that is not the case. Ah, yes, I hadn’t understood how you were testing. You’re right that = does not get redefined to use current-test-epsilon. Instead you would have to use your own equality predicate that incorporates it. test defines its approx-equal? as: (define (approx-equal? a b epsilon) (cond (( (abs a) (abs b)) (approx-equal? b a epsilon)) ((zero? b) ( (abs a) epsilon)) (else ( (abs (/ (- a b) b)) epsilon Which you could then add to your predicate like so: (define (list= l1 l2) (and (= (length l1) (length l2)) (let loop ((l1* l1) (l2* l2)) (cond ((null? l1*) #t) ((approx-equal? (car l1*) (car l2*) (current-test-epsilon)) (loop (cdr l1*) (cdr l2*))) (else #f) Easier: (define list= (let ((approx=? (current-test-comparator))) (lambda (ls1 ls2) (and (= (length ls1) (length ls2)) (every approx=? ls1 ls2) then (test-assert (list= '(0.655 0.843 0.200 1.0) (parse-color 167,215,51 #f))) or (define-syntax test-rgb (syntax-rules () ((test-rgb expected expr) (test-rgb #f expected expr)) ((test-rgb name expected expr) (parameterize ((current-test-comparator list=)) (test name expected expr) (test-rgb '(0.655 0.843 0.200 1.0) (parse-color 167,215,51 #f)) -- Alex ___ Chicken-users mailing list Chicken-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/chicken-users
