Mutually recursive local functions.

[Elifant]

Hello all.

Is it possible to write mutually recursive local functions in Nemerle?

def a()
b()

def b()
a()

gives "unbound name 'b'"

Known workarounds:
1. make them class methods (need to explicitly type them)
2. pass one as parameter to other (ugly)

Are there other possibilities?

[Sergei Tulentsev]

def a(p)
{
when(p > 0)
b(p - 1);
}
and b(p)
{
WriteLine(p);
a(p);
}

Post by Elifant
Hello all.
Is it possible to write mutually recursive local functions in Nemerle?
def a()
b()
def b()
a()
gives "unbound name 'b'"
1. make them class methods (need to explicitly type them)
2. pass one as parameter to other (ugly)
Are there other possibilities?
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[Elifant]

Post by Sergei Tulentsev
def a(p)
{
when(p > 0)
b(p - 1);
}
and b(p)
{
WriteLine(p);
a(p);
}

Cool! This is definitely must be somewere on the Wiki. May be it is, but
I couldn't find.

[Michal Moskal]

Post by Elifant
Cool! This is definitely must be somewere on the Wiki. May be it is, but
I couldn't find.

Go ahead and add it then :)

[Elifant]

Post by Michal Moskal

Post by Elifant
Cool! This is definitely must be somewere on the Wiki. May be it is, but
I couldn't find.

Go ahead and add it then :)

I've added it at
http://nemerle.org/Grok_Base_structure_of_programs#Local_functions,
but I can't think out simple and useful example of use. So I just wrote
dumb code.

[Radu Grigore]

Post by Elifant
I've added it at
http://nemerle.org/Grok_Base_structure_of_programs#Local_functions,
dumb code.

One (common?) use is to log the parameters and the return value of a
recursive function.

def fib(n)
if (n<2) n
else fib(n-1)+fib(n-2)

gets changed into

def fibNoLog(n)
if (n<2) n
else fib(n-1)+fib(n-2)
and fib(n)
def r = fibNoLog(n)
WriteLine($"fib($n)=$r")

The transformation is automatic and easy to do. Modifying a
complicated recursive function might not be as convenient especially
if it has multiple return points.