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<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"/><meta name="viewport" content="width=device-width, initial-scale=0.8"/><title>7.4 Inferred Linking</title><link rel="stylesheet" type="text/css" href="../scribble.css" title="default"/><link rel="stylesheet" type="text/css" href="extras.css" title="default"/><link rel="stylesheet" type="text/css" href="../racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-style.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../doc-site.css" title="default"/><script type="text/javascript" src="../scribble-common.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../doc-site.js"></script><script type="text/javascript" src="../local-redirect/local-redirect.js"></script><script type="text/javascript" src="../local-redirect/local-user-redirect.js"></script><!--[if IE 6]><style type="text/css">.SIEHidden { overflow: hidden; }</style><![endif]--></head><body id="doc-racket-lang-org"><div class="tocset"><div class="tocview"><div class="tocviewlist tocviewlisttopspace"><div class="tocviewtitle"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_0");">►</a></td><td></td><td><a href="index.html" class="tocviewlink" data-pltdoc="x">The Racket Reference</a></td></tr></table></div><div class="tocviewsublisttop" style="display: none;" id="tocview_0"><table cellspacing="0" cellpadding="0"><tr><td align="right">1 </td><td><a href="model.html" class="tocviewlink" data-pltdoc="x">Language Model</a></td></tr><tr><td align="right">2 </td><td><a href="notation.html" class="tocviewlink" data-pltdoc="x">Notation for Documentation</a></td></tr><tr><td align="right">3 </td><td><a href="syntax.html" class="tocviewlink" data-pltdoc="x">Syntactic Forms</a></td></tr><tr><td align="right">4 </td><td><a href="data.html" class="tocviewlink" data-pltdoc="x">Datatypes</a></td></tr><tr><td align="right">5 </td><td><a href="structures.html" class="tocviewlink" data-pltdoc="x">Structures</a></td></tr><tr><td align="right">6 </td><td><a href="mzlib_class.html" class="tocviewlink" data-pltdoc="x">Classes and Objects</a></td></tr><tr><td align="right">7 </td><td><a href="mzlib_unit.html" class="tocviewselflink" data-pltdoc="x">Units</a></td></tr><tr><td align="right">8 </td><td><a href="contracts.html" class="tocviewlink" data-pltdoc="x">Contracts</a></td></tr><tr><td align="right">9 </td><td><a href="match.html" class="tocviewlink" data-pltdoc="x">Pattern Matching</a></td></tr><tr><td align="right">10 </td><td><a href="control.html" class="tocviewlink" data-pltdoc="x">Control Flow</a></td></tr><tr><td align="right">11 </td><td><a href="concurrency.html" class="tocviewlink" data-pltdoc="x">Concurrency and Parallelism</a></td></tr><tr><td align="right">12 </td><td><a href="Macros.html" class="tocviewlink" data-pltdoc="x">Macros</a></td></tr><tr><td align="right">13 </td><td><a href="input-and-output.html" class="tocviewlink" data-pltdoc="x">Input and Output</a></td></tr><tr><td align="right">14 </td><td><a href="security.html" class="tocviewlink" data-pltdoc="x">Reflection and Security</a></td></tr><tr><td align="right">15 </td><td><a href="os.html" class="tocviewlink" data-pltdoc="x">Operating System</a></td></tr><tr><td align="right">16 </td><td><a href="memory.html" class="tocviewlink" data-pltdoc="x">Memory Management</a></td></tr><tr><td align="right">17 </td><td><a href="unsafe.html" class="tocviewlink" data-pltdoc="x">Unsafe Operations</a></td></tr><tr><td align="right">18 </td><td><a href="running.html" class="t
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unit.</div></p><p>Evaluating a reference to a <span class="RktVar">unit-id</span> bound by
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<span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._define-unit%29%29" class="RktStxLink" data-pltdoc="x">define-unit</a></span> produces a unit, just like evaluating an
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<span class="RktSym">id</span> bound by <span class="RktPn">(</span><span class="RktSym"><a href="define.html#%28form._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._define%29%29" class="RktStxLink" data-pltdoc="x">define</a></span><span class="stt"> </span><span class="RktSym">id</span><span class="stt"> </span><span class="RktPn">(</span><span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._unit%29%29" class="RktStxLink" data-pltdoc="x">unit</a></span><span class="stt"> </span><span class="RktMeta"><a href="stx-patterns.html#%28form._%28%28lib._racket%2Fprivate%2Fstxcase-scheme..rkt%29._......%29%29" class="RktStxLink" data-pltdoc="x">...</a></span><span class="RktPn">)</span><span class="RktPn">)</span>. In addition,
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however, <span class="RktVar">unit-id</span> can be used in <span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._compound-unit%2Finfer%29%29" class="RktStxLink" data-pltdoc="x">compound-unit/infer</a></span>.
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See <span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._unit%29%29" class="RktStxLink" data-pltdoc="x">unit</a></span> for information on <span class="RktVar">tagged-sig-spec</span>,
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<span class="RktVar">init-depends-decl</span>, and <span class="RktVar">unit-body-expr-or-defn</span>.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><table cellspacing="0" cellpadding="0" class="RktBlk RForeground"><tr><td><span class="RktPn">(</span><a name="(form._((lib._racket/unit..rkt)._compound-unit/infer))"></a><span title="Provided from: racket/unit, racket | Package: base"><span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._compound-unit%2Finfer%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">compound-unit/infer</a></span></span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._import%29%29" class="RktStxLink" data-pltdoc="x">import</a></span><span class="hspace"> </span><span class="RktVar">tagged-infer-link-import</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._export%29%29" class="RktStxLink" data-pltdoc="x">export</a></span><span class="hspace"> </span><span class="RktVar">tagged-infer-link-export</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._link%29%29" class="RktStxLink" data-pltdoc="x">link</a></span><span class="hspace"> </span><span class="RktVar">infer-linkage-decl</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr><tr><td><span class="stt"> </span></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="specgrammar"><tr><td align="right" valign="baseline"><span class="RktVar">tagged-infer-link-import</span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">=</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktVar">tagged-sig-id</span></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">|</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktPn">(</span><span class="RktVar">link-id</span><span class="hspace"> </span><span class="RktSym">:</span><span class="hspace"> </span><span class="RktVar">tagged-sig-id</span><span class="RktPn">)</span></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td></tr><tr><td align="right" valign="baseline"><span class="RktVar">tagged-infer-link-export</span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">=</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktPn">(</span><span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._tag%29%29" class="RktStxLink" data-pltdoc="x">tag</a></span><span class="hspace"> </span><span class="RktVar">id</span><span class="hspa
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<span class="RktSym"><a href="compoundunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._compound-unit%29%29" class="RktStxLink" data-pltdoc="x">compound-unit</a></span> and <span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._compound-unit%2Finfer%29%29" class="RktStxLink" data-pltdoc="x">compound-unit/infer</a></span> is that the
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<span class="RktVar">unit-expr</span> for a linked unit is replaced with a
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<span class="RktVar">unit-id</span>, where a <span class="RktVar">unit-id</span> is bound by
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<span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._define-unit%29%29" class="RktStxLink" data-pltdoc="x">define-unit</a></span> (or one of the other unit-binding forms that we
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introduce later in this section). Furthermore, an import can name just
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a <span class="RktVar">sig-id</span> without locally binding a <span class="RktVar">link-id</span>, and an
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export can be based on a <span class="RktVar">sig-id</span> instead of a
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<span class="RktVar">link-id</span>, and a declaration in the <span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._link%29%29" class="RktStxLink" data-pltdoc="x">link</a></span> clause can be
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simply a <span class="RktVar">unit-id</span> with no specified exports or imports.</div></p><p>The <span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._compound-unit%2Finfer%29%29" class="RktStxLink" data-pltdoc="x">compound-unit/infer</a></span> form expands to
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<span class="RktSym"><a href="compoundunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._compound-unit%29%29" class="RktStxLink" data-pltdoc="x">compound-unit</a></span> by adding <span class="RktSym">sig-ids</span> as needed to
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the <span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._import%29%29" class="RktStxLink" data-pltdoc="x">import</a></span> clause, by replacing <span class="RktVar">sig-id</span>s in the
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<span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._export%29%29" class="RktStxLink" data-pltdoc="x">export</a></span> clause by <span class="RktVar">link-id</span>s, and by completing
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the declarations of the <span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._link%29%29" class="RktStxLink" data-pltdoc="x">link</a></span> clause. This completion is based
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on static information associated with each
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<span class="RktVar">unit-id</span>. Links and exports can be inferred when all
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signatures exported by the linked units are distinct from each other
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and from all imported signatures, and when all imported signatures are
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distinct. Two signatures are <span style="font-style: italic">distinct</span> only if they
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share no ancestor through <span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._extends%29%29" class="RktStxLink" data-pltdoc="x">extends</a></span>.</p><p>The long form of a <span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._link%29%29" class="RktStxLink" data-pltdoc="x">link</a></span> declaration can be used to resolve
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ambiguity by giving names to some of a unit’s exports and supplying
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specific bindings for some of a unit’s imports. The long form need not
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name all of a unit’s exports or supply all of a unit’s imports if the
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remaining parts can be inferred.</p><p>When a unit declares initialization dependencies,
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<span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._compound-unit%2Finfer%29%29" class="RktStxLink" data-pltdoc="x">compound-unit/infer</a></span> checks that the <span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._link%29%29" class="RktStxLink" data-pltdoc="x">link</a></span> declaration
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is consistent with those dependencies, and it reports a syntax error if
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not.</p><p>Like <span class="RktSym"><a href="compoundunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._compound-unit%29%29" class="RktStxLink" data-pltdoc="x">compound-unit</a></span>, the <span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._compound-unit%2Finfer%29%29" class="RktStxLink" data-pltdoc="x">compound-unit/infer</a></span> form
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produces a (compound) unit without statically binding information
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about the result unit’s imports and exports. That is,
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<span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._compound-unit%2Finfer%29%29" class="RktStxLink" data-pltdoc="x">compound-unit/infer</a></span> consumes static information, but it does
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not generate it. Two additional forms,
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<span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._define-compound-unit%29%29" class="RktStxLink" data-pltdoc="x">define-compound-unit</a></span> and
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<span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._define-compound-unit%2Finfer%29%29" class="RktStxLink" data-pltdoc="x">define-compound-unit/infer</a></span>, generate static information
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(where the former does not consume static information).</p><p class="SHistory">Changed in version 6.1.1.8 of package <span class="stt">base</span>: Added static checking of the <span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._link%29%29" class="RktStxLink" data-pltdoc="x">link</a></span>
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clause with respect to declared
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initialization dependencies.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><table cellspacing="0" cellpadding="0" class="RktBlk RForeground"><tr><td><span class="RktPn">(</span><a name="(form._((lib._racket/unit..rkt)._define-compound-unit))"></a><span title="Provided from: racket/unit, racket | Package: base"><span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._define-compound-unit%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">define-compound-unit</a></span></span><span class="hspace"> </span><span class="RktVar">id</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._import%29%29" class="RktStxLink" data-pltdoc="x">import</a></span><span class="hspace"> </span><span class="RktVar">link-binding</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._export%29%29" class="RktStxLink" data-pltdoc="x">export</a></span><span class="hspace"> </span><span class="RktVar">tagged-link-id</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._link%29%29" class="RktStxLink" data-pltdoc="x">link</a></span><span class="hspace"> </span><span class="RktVar">linkage-decl</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Like <span class="RktSym"><a href="compoundunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._compound-unit%29%29" class="RktStxLink" data-pltdoc="x">compound-unit</a></span>, but binds static information about the
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compound unit like <span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._define-unit%29%29" class="RktStxLink" data-pltdoc="x">define-unit</a></span>, including the propagation of
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initialization-dependency information (on remaining inports) from the
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linked units.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><table cellspacing="0" cellpadding="0" class="RktBlk RForeground"><tr><td><span class="RktPn">(</span><a name="(form._((lib._racket/unit..rkt)._define-compound-unit/infer))"></a><span title="Provided from: racket/unit, racket | Package: base"><span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._define-compound-unit%2Finfer%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">define-compound-unit/infer</a></span></span><span class="hspace"> </span><span class="RktVar">id</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._import%29%29" class="RktStxLink" data-pltdoc="x">import</a></span><span class="hspace"> </span><span class="RktVar">link-binding</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._export%29%29" class="RktStxLink" data-pltdoc="x">export</a></span><span class="hspace"> </span><span class="RktVar">tagged-infer-link-export</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._link%29%29" class="RktStxLink" data-pltdoc="x">link</a></span><span class="hspace"> </span><span class="RktVar">infer-linkage-decl</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Like <span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._compound-unit%2Finfer%29%29" class="RktStxLink" data-pltdoc="x">compound-unit/infer</a></span>, but binds static information about
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the compound unit like <span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._define-compound-unit%29%29" class="RktStxLink" data-pltdoc="x">define-compound-unit</a></span>.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><table cellspacing="0" cellpadding="0" class="RktBlk RForeground"><tr><td><span class="RktPn">(</span><a name="(form._((lib._racket/unit..rkt)._define-unit-binding))"></a><span title="Provided from: racket/unit, racket | Package: base"><span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._define-unit-binding%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">define-unit-binding</a></span></span><span class="hspace"> </span><span class="RktVar">unit-id</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">unit-expr</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._import%29%29" class="RktStxLink" data-pltdoc="x">import</a></span><span class="hspace"> </span><span class="RktVar">tagged-sig-spec</span><span class="hspace"> </span><span class="RktMeta">...+</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktPn">(</span><span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._export%29%29" class="RktStxLink" data-pltdoc="x">export</a></span><span class="hspace"> </span><span class="RktVar">tagged-sig-spec</span><span class="hspace"> </span><span class="RktMeta">...+</span><span class="RktPn">)</span></td></tr><tr><td><span class="hspace"> </span><span class="RktVar">init-depends-decl</span><span class="RktPn">)</span></td></tr></table></blockquote></td></tr></table></blockquote></div><div class="SIntrapara">Like <span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._define-unit%29%29" class="RktStxLink" data-pltdoc="x">define-unit</a></span>, but the unit implementation is determined
|
||
|
|
from an existing unit produced by <span class="RktVar">unit-expr</span>. The imports and
|
||
|
|
exports of the unit produced by <span class="RktVar">unit-expr</span> must be consistent
|
||
|
|
with the declared imports and exports, otherwise the
|
||
|
|
<span class="RktSym"><a href="exns.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._exn~3afail~3acontract%29%29" class="RktValLink" data-pltdoc="x">exn:fail:contract</a></span> exception is raised when the <span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._define-unit-binding%29%29" class="RktStxLink" data-pltdoc="x">define-unit-binding</a></span>
|
||
|
|
form is evaluated.</div></p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._racket/unit..rkt)._invoke-unit/infer))"></a><span title="Provided from: racket/unit, racket | Package: base"><span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._invoke-unit%2Finfer%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">invoke-unit/infer</a></span></span><span class="hspace"> </span><span class="RktVar">unit-spec</span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="stt"> </span></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="specgrammar"><tr><td align="right" valign="baseline"><span class="RktVar">unit-spec</span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">=</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktVar">unit-id</span></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">|</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktPn">(</span><span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._link%29%29" class="RktStxLink" data-pltdoc="x">link</a></span><span class="hspace"> </span><span class="RktVar">link-unit-id</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Like <span class="RktSym"><a href="invokingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._invoke-unit%29%29" class="RktStxLink" data-pltdoc="x">invoke-unit</a></span>, but uses static information associated with
|
||
|
|
<span class="RktVar">unit-id</span> to infer which imports must be assembled from the
|
||
|
|
current context. If given a link form containing multiple
|
||
|
|
<span class="RktVar">link-unit-id</span>s, then the units are first linked via
|
||
|
|
<span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._define-compound-unit%2Finfer%29%29" class="RktStxLink" data-pltdoc="x">define-compound-unit/infer</a></span>.</div></p><p>When assembling imports from the current context, the <a href="syntax-model.html#%28tech._lexical._information%29" class="techoutside" data-pltdoc="x"><span class="techinside">lexical
|
||
|
|
information</span></a> of a <span class="RktVar">unit-id</span> is used for constructing the lexical
|
||
|
|
information of the signatures for the unit’s imports (i.e., the lexical
|
||
|
|
information that would normally be derived from the signature reference).
|
||
|
|
See <span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._define-signature%29%29" class="RktStxLink" data-pltdoc="x">define-signature</a></span> for more information.</p><p><div class="SIntrapara"><blockquote class="SVInsetFlow"><table cellspacing="0" cellpadding="0" class="boxed RBoxed"><tr><td><blockquote class="SubFlow"><div class="RBackgroundLabel SIEHidden"><div class="RBackgroundLabelInner"><p>syntax</p></div></div><p class="RForeground"><span class="RktPn">(</span><a name="(form._((lib._racket/unit..rkt)._define-values/invoke-unit/infer))"></a><span title="Provided from: racket/unit, racket | Package: base"><span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._define-values%2Finvoke-unit%2Finfer%29%29" class="RktStxDef RktStxLink" data-pltdoc="x">define-values/invoke-unit/infer</a></span></span><span class="hspace"> </span><span class="RktVar">maybe-exports</span><span class="hspace"> </span><span class="RktVar">unit-spec</span><span class="RktPn">)</span></p></blockquote></td></tr><tr><td><span class="stt"> </span></td></tr><tr><td><table cellspacing="0" cellpadding="0" class="specgrammar"><tr><td align="right" valign="baseline"><span class="RktVar">maybe-exports</span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">=</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><table cellspacing="0" cellpadding="0" class="RktBlk"><tr><td></td></tr></table></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">|</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktPn">(</span><span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._export%29%29" class="RktStxLink" data-pltdoc="x">export</a></span><span class="hspace"> </span><span class="RktVar">tagged-sig-spec</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td></tr><tr><td align="right" valign="baseline"><span class="RktVar">unit-spec</span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">=</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktVar">unit-id</span></td></tr><tr><td align="right" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="center" valign="baseline">|</td><td align="left" valign="baseline"><span class="stt"> </span></td><td align="left" valign="baseline"><span class="RktPn">(</span><span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._link%29%29" class="RktStxLink" data-pltdoc="x">link</a></span><span class="hspace"> </span><span class="RktVar">link-unit-id</span><span class="hspace"> </span><span class="RktMeta">...</span><span class="RktPn">)</span></td></tr></table></td></tr></table></blockquote></div><div class="SIntrapara">Like <span class="RktSym"><a href="invokingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._define-values%2Finvoke-unit%29%29" class="RktStxLink" data-pltdoc="x">define-values/invoke-unit</a></span>, but uses static information
|
||
|
|
associated with <span class="RktVar">unit-id</span> to infer which imports must be
|
||
|
|
assembled from the current context and, if no <span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._export%29%29" class="RktStxLink" data-pltdoc="x">export</a></span> clause
|
||
|
|
is present, which exports should be bound by the definition. If given
|
||
|
|
a link form containing multiple <span class="RktVar">link-unit-id</span>s, then the units
|
||
|
|
are first linked via <span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._define-compound-unit%2Finfer%29%29" class="RktStxLink" data-pltdoc="x">define-compound-unit/infer</a></span>.</div></p><p>Similar to <span class="RktSym"><a href="linkinference.html#%28form._%28%28lib._racket%2Funit..rkt%29._invoke-unit%2Finfer%29%29" class="RktStxLink" data-pltdoc="x">invoke-unit/infer</a></span>, the <a href="syntax-model.html#%28tech._lexical._information%29" class="techoutside" data-pltdoc="x"><span class="techinside">lexical information</span></a>
|
||
|
|
of a <span class="RktVar">unit-id</span> is used for constructing the lexical information
|
||
|
|
of the signatures for the unit’s inferred imports and inferred exports
|
||
|
|
(i.e., the lexical information that would normally be derived from a
|
||
|
|
signature reference). See <span class="RktSym"><a href="creatingunits.html#%28form._%28%28lib._racket%2Funit..rkt%29._define-signature%29%29" class="RktStxLink" data-pltdoc="x">define-signature</a></span> for more
|
||
|
|
information.</p><div class="navsetbottom"><span class="navleft"><form class="searchform"><input class="searchbox" id="searchbox" type="text" tabindex="1" placeholder="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "8.6", "../");"/></form> <a href="https://docs.racket-lang.org/index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("8.6");">top</a><span class="tocsettoggle"> <a href="javascript:void(0);" title="show/hide table of contents" onclick="TocsetToggle();">contents</a></span></span><span class="navright"> <a href="compoundunits.html" title="backward to "7.3 Linking Units and Creating Compound Units"" data-pltdoc="x">← prev</a> <a href="mzlib_unit.html" title="up to "7 Units"" data-pltdoc="x">up</a> <a href="Generating_A_Unit_from_Context.html" title="forward to "7.5 Generating A Unit from Context"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html>
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