[erlang-questions] Core erlang wildcards and sequences

amindfv <>
Thu Aug 1 15:51:57 CEST 2013



El Jul 31, 2013, a las 15:02, "Ludovic Demblans" <> escribió:

> Hi everybody,
> 
> I'm building a small DSL which compiles to Erlang VM. I have two
> questions about how to achieve this.
> 
> First, if i want compile this pseudo code
> 
>    a = something
>    b = do_something_with(a) %% involves a
>    ... rest of code ...
> 
> I end to build the following (pseudo) core erlang code:
> 
>    let A = something
>        in let B = apply do_something_with(A)
>            in ... rest of code
> 
> I printed dummy erlang code to core erlang representation and it
> resulted in the same forms, namely a stack of 'let expressions'.
> 
> Is that ok ? Are there better ways to achieve this in certain situations ?
> 


Core erlang has "letrec", so you shouldn't have to nest those let statements.


> 
> Then, i want to implement wildcards ( _ ), so in core erlang i create
> a regular variable (which is never used) to match any value. Again, is
> there a better way to do this, does one more variable involves more
> overhead (i assume the compiler will optimize it anyway) ?
> 
> One more question !! I figured out that operators like + are calls to
> erlang:'+'. I would like to play with the cons opearator but neither
> erlang:'|' nor erlang:'cons' seems to exist. Is there another name ?
> This is not important, just for fun.
> 

Afaik, [ foo | bar ] is as desugared as it gets -- weird, I know.


> Thank you
> 
> ludovic
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> 
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Tom


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