26 lines
784 B
ReStructuredText
26 lines
784 B
ReStructuredText
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Boolean Language
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================
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The Boolean language allows the user to define simple Boolean expressions that
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Dune can evaluate. Here's a semiformal specification of the language:
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.. productionlist:: blang
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op : '=' | '<' | '>' | '<>' | '>=' | '<='
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expr : (and <expr>+)
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: (or <expr>+)
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: (<op> <template> <template>)
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: (not <expr>)
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: <template>
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After an expression is evaluated, it must be exactly the string ``true`` or
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``false`` to be considered as a Boolean. Any other value will be treated as an
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error.
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Below is a simple example of a condition expressing that the build
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has a Flambda compiler, with the help of variable expansion, and is
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targeting OSX:
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.. code:: dune
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(and %{ocaml-config:flambda} (= %{ocaml-config:system} macosx))
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