[e-lang] Bug?: escape-catch doesn't work at all

[Mark S. Miller]

Kevin Reid wrote:
> ? escape e { e(1) } catch v { println(`caught $v`) }
> # value: 1
> 
> Tested with E-on-Java 0.9.1b, 0.8.37d, and 0.8.35f.
> 
> Is this a bug, or am I confused about how escape-catch works?


It is a bug, but not where expected. The interpretation of an EscapeExpr works 
fine. The bug is in the source-to-source optimization performed by 
BindFramesVisitor#visitEscapeExpr. This optimization properly optimizes

     escape e { e(1) }

first to

     escape e { 1 }

and then to

     1

However, it was also optimizing

     escape e { e(1) } catch v { println(`caught $v`) }

to

     escape e { 1 } catch v { println(`caught $v`) }

which is wrong. It's now fixed (though not yet committed or released):

     ? escape e { e(1) } catch v { println(`caught $v`) }
     # stdout: caught 1
     #

Thanks for catching this!


-- 
Text by me above is hereby placed in the public domain

     Cheers,
     --MarkM