<html> <head> <style></style></head> <body class='hmmessage'><div dir='ltr'><p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;">Hello,<p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;"> <p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;">I recently posted this as a Stackoverflow question, but upon the advice of some of the commenters, I've decided to ask here instead. The SO question, for reference, is this one: <a href="http://stackoverflow.com/questions/13449842/why-doesnt-dr-racket-expand-nested-macros">http://stackoverflow.com/questions/13449842/why-doesnt-dr-racket-expand-nested-macros</a><p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;"> <p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;">What follows is the text of the question:<p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;">__________________________________________________________________________________________<p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;"> <p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;">I am using Dr. Racket, version 5.3.1. I am trying to use the Macro Stepper feature, and am having problems with "nested" macros. (By "nested" macros, I mean macros that expand to a form which contains more (used-defined) macros. I don't know if this is the correct terminology). The macro stepper only expands these macros once, and then doesn't bother to continue expanding.<p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;"> <p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;">For example, I type the following into the Dr. Racket definitions area:<pre style="margin-top: 0px; margin-bottom: 10px; padding: 5px; border: 0px; font-size: 14px; vertical-align: baseline; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; overflow: auto; width: auto; max-height: 600px; line-height: 18px; background-color: rgb(238, 238, 238);"><code style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif;">#lang racket (define-syntax foo (syntax-rules () ((foo a) 1) ((foo a stuff ...) (+ 1 (foo stuff ...))))) (foo a b c d e) </code></pre><p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;">Running this returns 5, as expected. Furthermore, typing <code style="margin: 0px; padding: 1px 5px; border: 0px; vertical-align: baseline; background-color: rgb(238, 238, 238); font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif;">(expand '(foo a b c d e))</code> in the Interactions window yields the syntax <code style="margin: 0px; padding: 1px 5px; border: 0px; vertical-align: baseline; background-color: rgb(238, 238, 238); font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif;">'(#%app + '1 (#%app + '1 (#%app + '1 (#%app + '1 '1))))</code>, also as expected. However, going into the Macro Stepper (with standard macro hiding) and pressing the <code style="margin: 0px; padding: 1px 5px; border: 0px; vertical-align: baseline; background-color: rgb(238, 238, 238); font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif;">End</code> button, I only see <code style="margin: 0px; padding: 1px 5px; border: 0px; vertical-align: baseline; background-color: rgb(238, 238, 238); font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif;">(+ 1 (foo b c d e))</code>. If I disable macro hiding, I get the expected result, but also a whole lot of line noise that I'd rather not see.<p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;"> <p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;">Is this a bug, or expected behaviour? I swear that Dr. Racket didn't used to behave like this...<p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;"> <p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;">I actual submitted a bug report about this a month ago (<a href="http://bugs.racket-lang.org/query/?cmd=view&pr=13203" rel="nofollow" style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; background-color: transparent; color: rgb(74, 107, 130); text-decoration: initial; cursor: pointer;">http://bugs.racket-lang.org/query/?cmd=view&pr=13203</a>), but then I started having second thoughts about whether it was a bug or not, so I decided to ask here.<p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;"> <p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;">PS - other random notes about this:<p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;"> <p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;">It seems to depend on whether or not the nested macro is the outer-most expression in the expanded form. For example, if I define (in addition to foo):<pre style="margin-top: 0px; margin-bottom: 10px; padding: 5px; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(238, 238, 238); font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; overflow: auto; width: auto; max-height: 600px; line-height: 18px;"><code style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif;">(define-syntax bar (syntax-rules () ((bar xs ...) (foo xs ...)))) (define-syntax baz (syntax-rules () ((baz xs ...) (bar xs ...)))) (baz a b c d e) </code></pre><p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;">Then the macro stepper shows me that <code style="margin: 0px; padding: 1px 5px; border: 0px; vertical-align: baseline; background-color: rgb(238, 238, 238); font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif;">(baz a b c d e)</code> expands to <code style="margin: 0px; padding: 1px 5px; border: 0px; vertical-align: baseline; background-color: rgb(238, 238, 238); font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif;">(bar a b c d e)</code> to <code style="margin: 0px; padding: 1px 5px; border: 0px; vertical-align: baseline; background-color: rgb(238, 238, 238); font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif;">(foo a b c d e)</code> to <code style="margin: 0px; padding: 1px 5px; border: 0px; vertical-align: baseline; background-color: rgb(238, 238, 238); font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif;">(+ 1 (foo b c d e))</code>, but then it stops.<p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;"> <p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;">The previous example might make you think it has something to do with macros that expand to themselves, but this doesn't appear to be the case. For example, if I redefine foo as follows:<pre style="margin-top: 0px; margin-bottom: 10px; padding: 5px; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(238, 238, 238); font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; overflow: auto; width: auto; max-height: 600px; line-height: 18px;"><code style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif;">(define-syntax foo (syntax-rules () ((foo a) 1) ((foo a stuff ...) (+ 1 (blah stuff ...))))) </code></pre><p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;">With<pre style="margin-top: 0px; margin-bottom: 10px; padding: 5px; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(238, 238, 238); font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; overflow: auto; width: auto; max-height: 600px; line-height: 18px;"><code style="margin: 0px; padding: 0px; border: 0px; vertical-align: baseline; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif;">(define-syntax blah (syntax-rules () ((blah xs ...) 10))) </code></pre><p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;">Then <code style="margin: 0px; padding: 1px 5px; border: 0px; vertical-align: baseline; background-color: rgb(238, 238, 238); font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif;">(foo a b c d e)</code> expands to <code style="margin: 0px; padding: 1px 5px; border: 0px; vertical-align: baseline; background-color: rgb(238, 238, 238); font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif;">(+ 1 (blah b c d e))</code> and then stops.<p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;">__________________________________________________________________________________________<p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;"> <p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;">Thank you for your help,<p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;"> <p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;">Sandro<p style="margin-bottom: 1em; border: 0px; font-size: 14px; vertical-align: baseline; background-color: rgb(255, 255, 255); clear: both; word-wrap: break-word; font-family: Arial, 'Liberation Sans', 'DejaVu Sans', sans-serif; line-height: 18px;"> </div></body> </html>