HCoop / hcoop / debian / mlton.git / blame
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| 22 | <a href="./Home">MLton 20180207</a>\r | |
| 23 | </div>\r | |
| 24 | </div>\r | |
| 25 | <div id="header">\r | |
| 26 | <h1>MLBasisAnnotationExamples</h1>\r | |
| 27 | </div>\r | |
| 28 | <div id="content">\r | |
| 29 | <div id="preamble">\r | |
| 30 | <div class="sectionbody">\r | |
| 31 | <div class="paragraph"><p>Here are some example uses of <a href="MLBasisAnnotations">MLBasisAnnotations</a>.</p></div>\r | |
| 32 | </div>\r | |
| 33 | </div>\r | |
| 34 | <div class="sect1">\r | |
| 35 | <h2 id="_eliminate_spurious_warnings_in_automatically_generated_code">Eliminate spurious warnings in automatically generated code</h2>\r | |
| 36 | <div class="sectionbody">\r | |
| 37 | <div class="paragraph"><p>Programs that automatically generate source code can often produce\r | |
| 38 | nonexhaustive patterns, relying on invariants of the generated code to\r | |
| 39 | ensure that the pattern matchings never fail. A programmer may wish\r | |
| 40 | to elide the nonexhaustive warnings from this code, in order that\r | |
| 41 | legitimate warnings are not missed in a flurry of false positives. To\r | |
| 42 | do so, the programmer simply annotates the generated code with the\r | |
| 43 | <span class="monospaced">nonexhaustiveBind ignore</span> and <span class="monospaced">nonexhaustiveMatch ignore</span>\r | |
| 44 | annotations:</p></div>\r | |
| 45 | <div class="listingblock">\r | |
| 46 | <div class="content monospaced">\r | |
| 47 | <pre>local\r | |
| 48 | $(GEN_ROOT)/gen-lib.mlb\r | |
| 49 | \r | |
| 50 | ann\r | |
| 51 | "nonexhaustiveBind ignore"\r | |
| 52 | "nonexhaustiveMatch ignore"\r | |
| 53 | in\r | |
| 54 | foo.gen.sml\r | |
| 55 | end\r | |
| 56 | in\r | |
| 57 | signature FOO\r | |
| 58 | structure Foo\r | |
| 59 | end</pre>\r | |
| 60 | </div></div>\r | |
| 61 | </div>\r | |
| 62 | </div>\r | |
| 63 | <div class="sect1">\r | |
| 64 | <h2 id="_deliver_a_library">Deliver a library</h2>\r | |
| 65 | <div class="sectionbody">\r | |
| 66 | <div class="paragraph"><p>Standard ML libraries can be delivered via <span class="monospaced">.mlb</span> files. Authors of\r | |
| 67 | such libraries should strive to be mindful of the ways in which\r | |
| 68 | programmers may choose to compile their programs. For example,\r | |
| 69 | although the defaults for <span class="monospaced">sequenceNonUnit</span> and <span class="monospaced">warnUnused</span> are\r | |
| 70 | <span class="monospaced">ignore</span> and <span class="monospaced">false</span>, periodically compiling with these annotations\r | |
| 71 | defaulted to <span class="monospaced">warn</span> and <span class="monospaced">true</span> can help uncover likely bugs. However,\r | |
| 72 | a programmer is unlikely to be interested in unused modules from an\r | |
| 73 | imported library, and the behavior of <span class="monospaced">sequenceNonUnit error</span> may be\r | |
| 74 | incompatible with some libraries. Hence, a library author may choose\r | |
| 75 | to deliver a library as follows:</p></div>\r | |
| 76 | <div class="listingblock">\r | |
| 77 | <div class="content monospaced">\r | |
| 78 | <pre>ann\r | |
| 79 | "nonexhaustiveBind warn" "nonexhaustiveMatch warn"\r | |
| 80 | "redundantBind warn" "redundantMatch warn"\r | |
| 81 | "sequenceNonUnit warn"\r | |
| 82 | "warnUnused true" "forceUsed"\r | |
| 83 | in\r | |
| 84 | local\r | |
| 85 | file1.sml\r | |
| 86 | ...\r | |
| 87 | filen.sml\r | |
| 88 | in\r | |
| 89 | functor F1\r | |
| 90 | ...\r | |
| 91 | signature S1\r | |
| 92 | ...\r | |
| 93 | structure SN\r | |
| 94 | ...\r | |
| 95 | end\r | |
| 96 | end</pre>\r | |
| 97 | </div></div>\r | |
| 98 | <div class="paragraph"><p>The annotations <span class="monospaced">nonexhaustiveBind warn</span>, <span class="monospaced">redundantBind warn</span>,\r | |
| 99 | <span class="monospaced">nonexhaustiveMatch warn</span>, <span class="monospaced">redundantMatch warn</span>, and <span class="monospaced">sequenceNonUnit\r | |
| 100 | warn</span> have the obvious effect on elaboration. The annotations\r | |
| 101 | <span class="monospaced">warnUnused true</span> and <span class="monospaced">forceUsed</span> work in conjunction — warning on\r | |
| 102 | any identifiers that do not contribute to the exported modules, and\r | |
| 103 | preventing warnings on exported modules that are not used in the\r | |
| 104 | remainder of the program. Many of the\r | |
| 105 | <a href="MLBasisAvailableLibraries">available libraries</a> are delivered with\r | |
| 106 | these annotations.</p></div>\r | |
| 107 | </div>\r | |
| 108 | </div>\r | |
| 109 | </div>\r | |
| 110 | <div id="footnotes"><hr></div>\r | |
| 111 | <div id="footer">\r | |
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| 113 | </div>\r | |
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| 115 | </div>\r | |
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| 117 | </body>\r | |
| 118 | </html>\r |