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POHow do I design and load my Prolog source files so I don't have to manually use_module?
 

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  1. POHow do I design and load my Prolog source files so I don't have to manually use_module?
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    <p>I have a source file, openpage.pl, where I call use_module/1 to "import" SWI-Prolog's http_open/3:</p> <pre><code>use_module(library(http/http_open)). request(URL, In) :- http_open(URL, In, []), copy_stream_data(In, user_output), close(In). </code></pre> <p>It loads without complaint. However, try as I might, I can't run it the rules in it.</p> <pre><code>?- [openpage]. % openpage compiled 0.00 sec, 1,828 bytes true. ?- request('http://www.google.com', In). ERROR: request/2: Undefined procedure: http_open/3 ?- use_module(library(http/http_open)). true. ?- request('http://www.google.com', In). ERROR: request/2: Undefined procedure: http_open/3 ?- make. % Scanning references for 1 possibly undefined predicates Warning: The predicates below are not defined. If these are defined Warning: at runtime using assert/1, use :- dynamic Name/Arity. Warning: Warning: http_open/3, which is referenced by Warning: status/2 at /home/dale/sesame_test/prolog/openpage.pl:16 Warning: request/2 at /home/dale/sesame_test/prolog/openpage.pl:3 Warning: modified/2 at /home/dale/sesame_test/prolog/openpage.pl:7 true. ?- [openpage]. % openpage compiled 0.00 sec, 616 bytes true. ?- request('http://www.google.com', In). ERROR: request/2: Undefined procedure: http_open/3 ?- [forced] Action (h for help) ? exit </code></pre> <p>So in my next session, I invoke use_module/1 before loading my source file, and all is fine:</p> <pre><code>?- use_module(library(http/http_open)). % library(uri) compiled into uri 0.00 sec, 199,772 bytes % library(readutil) compiled into read_util 0.00 sec, 10,312 bytes % library(socket) compiled into socket 0.00 sec, 6,376 bytes % library(option) compiled into swi_option 0.00 sec, 7,748 bytes % library(base64) compiled into base64 0.00 sec, 9,776 bytes % library(debug) compiled into prolog_debug 0.01 sec, 12,056 bytes % library(http/http_open) compiled into http_open 0.01 sec, 282,844 bytes true. ?- [openpage]. % openpage compiled 0.00 sec, 1,380 bytes true. ?- request('http://www.google.com/', In). &lt;!doctype html&gt;&lt;html itemscope itemtype="http://schema.org/WebPage"&gt; ... In = &lt;stream&gt;(0x9366508). </code></pre> <p>How can I set up and execute my files so that I don't need this manual step of loading modules before loading my own code?</p>
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