Re: spend a lot of time with alex generated module

ivan gomez rodriguez <[email protected]> Wed, 16 Aug 2006 18:45:53 +0200

Newsgroups	gmane.comp.lang.haskell.hat
Message-ID	<[email protected]>

Malcolm Wallace wrote:
> kgu <[email protected]> wrote:
>
>   
>> hat-trans spends a lot of time (really a lot of time) in generate
>> module from a module generated by alex. The original module has 330
>> lines of code and module generated by hat-trans has 40700 !!.
>>     
>
> It is well-known that giving a machine-generated input to any
> compiler-like tool is the best way to show up its weaknesses!  I suppose
> the output from Alex is very different from the kind of code that a
> human would write.  Since Alex creates essentially a table-driven
> lexical analyser, it is possible that a large static description of the
> tables is where hat-trans is spending lots of time.  Also, if the
> Alex-generated code is deeply nested, hat-trans may spend too much time
> trying to pretty-print its output within 80 columns, when really the
> formatting will not fit nicely into such a small width.
>
> Just some ideas.  If you want to send a copy of the original Alex
> specification, we may be able to investigate further.
>
> Regards,
>     Malcolm
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> http://www.haskell.org/mailman/listinfo/hat
>
>   
I attach original specification.It's a very simple lexer specification. 
I had  some problem to compile module generated by hat-trans , it spends 
a lot of time too and it did not compile.

Thanks for your help and your job, i'm developing a compiler and hat is 
a really useful tool for me, it's a great tool!

Thanks,
Iván

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Lexer.x (text/plain, 2.5 KB)

{
module Lexer (Token(..), alexScanTokens) where
}

%wrapper "basic"

$digit = 0-9                    -- digits
$alpha = [a-zA-Z]               -- alphabetic characters

tokens :-
 
  $white+            ;
  "--".*             ;
  \.                { \s -> TPUNTO }
  \)                { \s -> TPARDER }
  \(                { \s -> TPARIZQ }
  \[                { \s -> TCORIZQ }
  \]                { \s -> TCORDER }
  \|                { \s -> TPIPE } 
  =                { \s -> TIGUAL }
  !=               { \s -> TDISTINTO }
  "->"                 { \s -> TFLECHA }
  >                { \s -> TMAYOR }
  >=               { \s -> TMAYORIGUAL }
  \<                { \s -> TMENOR }
  \<=               { \s -> TMENORIGUAL }
  \+               { \s -> TMAS }
  \-                { \s -> TMENOS }
  \*               { \s -> TPOR }
  \/                 { \s -> TBARRA }
  &                  { \s -> TAND } 
  \^                 { \s -> TTILDE }
  \,                { \s -> TCOMA }
  \;                { \s -> TPUNTOCOMA }
  :=                 { \s -> TDOSIGUAL }
  ::                 { \s -> TCUATROPUNTOS }
  \;\;                 { \s -> TDOSPUNTOCOMA }
  :                { \s -> TDOSPUNTOS }
  []                 { \s -> TCORCHETES }
  null               { \s -> TNULL }
  Int                { \s -> TINT }
  String             { \s -> TSTRING }
  in                 { \s -> TIN }
  let                { \s -> TLET }
  rec                { \s -> TISREC }
  case               { \s -> TCASE }
  of                 { \s -> TOF }
  if                 { \s -> TIF } 
  then               { \s -> TTHEN }
  else               { \s -> TELSE }
  "\""['A'-'Z''a'-'z''0'-'9''_'' ']* "\""
                     {  \s -> TCADENA s }
  $digit+            {  \s -> TENTERO (read s) }
  $alpha [$alpha $digit \_ \']*		
		     { \s -> TVAR s }	

  eof                {  \s -> TEOF }
 
{  
data Token 
	= TBLANCO
	| TCOMMENT 
 	| TPUNTO
   	| TPARIZQ 
   	| TPARDER 
   	| TCORIZQ 
   	| TCORDER 
   	| TPIPE  
        | TAMBER
   	| TIGUAL
        | TDISTINTO 
   	| TFLECHA 
   	| TMAYOR
        | TMAYORIGUAL 
   	| TMENOR 
        | TMENORIGUAL
   	| TMAS 
   	| TMENOS 
   	| TPOR 
   	| TBARRA 
   	| TTILDE 
   	| TCOMA 
  	| TPUNTOCOMA 
   	| TDOSIGUAL 
   	| TCUATROPUNTOS 
   	| TDOSPUNTOCOMA 
   	| TDOSPUNTOS 
   	| TCORCHETES 
        | TNULL
   	| TAND 
   	| TINT 
   	| TSTRING 
   	| TIN 
   	| TLET 
   	| TISREC 
   	| TCASE 
   	| TOF 
   	| TIF
        | TTHEN 
        | TELSE
        | TCADENA String 
   	| TENTERO Int 
   	| TVAR String
   	| TEOF 
	deriving (Eq,Show)

}