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>6.2. Compilation-Time Tips</A
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><P
>We have found that compiling parsers generated by
<SPAN
CLASS="APPLICATION"
>Happy</SPAN
> can take a large amount of time/memory, so
here's some tips on making things more sensible:</P
><P
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><P
> Include as little code as possible in the module
trailer. This code is included verbatim in the generated
parser, so if any of it can go in a separate module, do
so.</P
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> Give type signatures for everything (see <A
HREF="sec-type-signatures.html"
>Section 2.4</A
>. This is reported to improve
things by about 50%. If there is a type signature for every
single non-terminal in the grammar, then <SPAN
CLASS="APPLICATION"
>Happy</SPAN
>
automatically generates type signatures for most functions
in the parser.</P
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><P
> Simplify the grammar as much as possible (applies to
everything, this one).</P
></LI
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><P
> Use a recent version of GHC. Versions from 4.04
onwards have lower memory requirements for compiling
<SPAN
CLASS="APPLICATION"
>Happy</SPAN
>-generated parsers.</P
></LI
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><P
> Using <SPAN
CLASS="APPLICATION"
>Happy</SPAN
>'s <TT
CLASS="LITERAL"
>-g -a -c</TT
>
options when generating parsers to be compiled with GHC will
help considerably.</P
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