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Source for wiki Srfi17ExtensionsCowan version 1

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cowan

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127.11.51.1

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Srfi17ExtensionsCowan

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== Macros ==

Here are a few macros that extend [http://srfi.schemers.org/srfi-17/srfi-17.html SRFI 17] getters and setters.  

`(push! `''variable item''`)`

Calls `cons` on the values of ''item'' and ''variable'', and sets ''variable'' to the result.  Returns an unspecified value.

`(push! (`''proc arg'' ...`)` ''item''`)`

Calls `cons` on the values of ''item'' and `(`''proc arg'' ...`)`. Then evaluates `((setter `''proc''`)` ''arg'' ... ''result''`)`, where ''result'' is the newly allocated pair.   Returns an unspecified value.  It is an error if ''proc'' does not have an associated setter.

`(pop! `''variable''`)`

Calls `car` and `cdr` on the value of ''variable'', and sets ''variable'' to the result of `cdr`.  Returns the result of `car`.  It is an error if the value of ''variable'' is not a pair.

`(pop! (`''proc arg'' ...`))`

Calls `car` and `cdr` on the value of `(`''proc arg'' ...`)`. Then evaluates `((setter `''proc''`)` ''arg'' ... ''cdr-result''`)`, where ''cdr-result'' is the result of `cdr`.   Returns the result of `car`.  It is an error if the value of ''variable'' is not a pair.  It is also an error if ''proc'' does not have an associated setter.

`(inc! `''variable'' [ ''delta'' ]`)`

`(dec! `''variable'' [ ''delta'' ]`)`

Calls `+` on the values of ''variable'' and ''delta'', and sets ''variable'' to the result.  Returns an unspecified value.  It is an error if the value of ''variable'' is not a number.  The default value of ''delta'' is 1 for `inc!` and -1 for `dec!`.

`(inc! (`''proc arg'' ...`)` [ ''delta'' ]`)`

`(dec! (`''proc arg'' ...`)` [ ''delta'' ]`)`

Calls `+` on the values of `(`''proc arg'' ...`)` and ''delta''. Then evaluates `((setter `''proc''`)` ''arg'' ... ''result''`)`, where ''cdr-result'' is the result of `+`.   Returns an unspecified value.  The default value of ''delta'' is 1 for `inc!` and -1 for `dec!`.  It is an error if the value of ''variable'' is not a number.  It is also an error if ''proc'' does not have an associated setter.

`(update! `''variable proc''`)`

Applies the value of ''proc'' to the value of ''variable'', and sets ''variable'' to the result.  Returns an unspecified value.  It is an error if the value of ''proc'' is not a procedure that accepts one argument.

`(update! (`''proc arg'' ...`)` ''item''`)`

Applies ''proc'' to the values of ''item'' and `(`''proc arg'' ...`)`. Then evaluates `((setter `''proc''`)` ''arg'' ... ''result''`)`, where ''result'' is the result.   Returns an unspecified value.  It is an error if the value of ''proc'' is not a procedure that accepts one argument.  It is also an error if ''proc'' does not have an associated setter.

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2014-11-23 09:36:58