D
Don Y
Hi James,
A translation of the Limbo code appears at the end. Expecting *me*
to come up with a C version that uses features THAT I DIDN'T KNOW
EXISTED as of a few hours ago would be as prepostrous as me asking
you to tell me why C's approach is better than a Limbo approach --
and expecting *you* to provide that Limbo example! (assuming you've
never seen Limbo code until the same point in this thread that *I*
Exactly. I have no interest in waiting for a C2011 implementation
greetings(
surname: string, # parameter of type "string"
children: list of (string, int) # a list of tuples each
# consisting of a string and an int
output: chan of string # communication channel named "output"
# that conveys strings
) {
# create a string by concatenating the two string constants
# with the string *variable* passed to the function as "surname"
# pass the resulting string out the channel named "output"
output <-= "Season's Greetings from the "
+ surname + " family!\n";
# as long as the "children" list is not empty...
while (children != nil) {
# extract one the first ("head") element from the "children"
# list assigning it's component values to "firstname" and "int"
# the presence of the ':' is a syntactic shortcut that allows
# the declaration of these variables to be deduced from the
# values assigned to them (i.e., we know children consists
# of (string, int) tuples so we know "firstname" is now declared
# as a string and "age" is an int. I.e., this just saves two
# lines declaring those types as
# firstname: string;
# age: int;
(firstname, age) := hd children;
# ':' tells you that description is of the same type as the
# rvalue -- a string (since the expression on the right is
# recognizable as a string). Set the description string
# variable to the concatenation of the "firstname" and "surname"
# strings -- with a constant string (whitespace) in the middle
description := firstname + " " + surname;
# tack on the parenthetical comment indicating the child's age
# note the use of '=' instead of ":=" -- since we have already
# declared description's type
description = description
+ " (" + age + " years old)";
# pass the "fullname" (grrr... should have been "description")
# string to the communication channel named "output"
output <-= fullname;
# assign the balance (everything beyond the "head") of the children
# list to the children list variable
children = tl children;
}
}
logging(
input: chan of string # communication channel named "input"
# that conveys 'strings'
) {
sys = load Sys Sys->PATH; # a variable that holds a reference to
# a module called Sys. Sys->PATH
# is a constant defined within that
# module indicating where it is
while (FOREVER) {
# text is a string (because it's type is derived from the
# rhs type -- which is "chan of string"
# It's value is assigned from the string fetched from the
# communication channel named "input"
text :=<- input;
# use the print() member of the module referenced by "sys"
# to print a string "somewhere" (i.e., like printf)
sys->print("%s\n", text)
}
}
job(surname: string,
children: list of (string, int) # you've seen this before...
) {
pipe: channel of string; # declare "pipe" to be a communication
# channel (should have been "chan") that
# conveys "string" data types.
# create a thread that executes the "logging" function (defined
# above). Pass it a communication channel that it will use to
# watch for incoming text
spawn logging(pipe);
# create a thread that executes the "greetings" function (defined
# above). Pass it the communication channel that it should use
# to interact with the "logging" function started above. Pass
# the surname and list of children's (names, ages) to that
# function (i.e., thread) so that it has some work to do.
spawn greetings(surname, children, pipe)
...
}
I.e., anything that doesn't say "chan" or "spawn" in the above
is "application" and unrelated to the tasking aspects of the
language.
A translation of the Limbo code appears at the end. Expecting *me*
to come up with a C version that uses features THAT I DIDN'T KNOW
EXISTED as of a few hours ago would be as prepostrous as me asking
you to tell me why C's approach is better than a Limbo approach --
and expecting *you* to provide that Limbo example! (assuming you've
never seen Limbo code until the same point in this thread that *I*
was informed of said:
Exactly. I have no interest in waiting for a C2011 implementation
greetings(
surname: string, # parameter of type "string"
children: list of (string, int) # a list of tuples each
# consisting of a string and an int
output: chan of string # communication channel named "output"
# that conveys strings
) {
# create a string by concatenating the two string constants
# with the string *variable* passed to the function as "surname"
# pass the resulting string out the channel named "output"
output <-= "Season's Greetings from the "
+ surname + " family!\n";
# as long as the "children" list is not empty...
while (children != nil) {
# extract one the first ("head") element from the "children"
# list assigning it's component values to "firstname" and "int"
# the presence of the ':' is a syntactic shortcut that allows
# the declaration of these variables to be deduced from the
# values assigned to them (i.e., we know children consists
# of (string, int) tuples so we know "firstname" is now declared
# as a string and "age" is an int. I.e., this just saves two
# lines declaring those types as
# firstname: string;
# age: int;
(firstname, age) := hd children;
# ':' tells you that description is of the same type as the
# rvalue -- a string (since the expression on the right is
# recognizable as a string). Set the description string
# variable to the concatenation of the "firstname" and "surname"
# strings -- with a constant string (whitespace) in the middle
description := firstname + " " + surname;
# tack on the parenthetical comment indicating the child's age
# note the use of '=' instead of ":=" -- since we have already
# declared description's type
description = description
+ " (" + age + " years old)";
# pass the "fullname" (grrr... should have been "description")
# string to the communication channel named "output"
output <-= fullname;
# assign the balance (everything beyond the "head") of the children
# list to the children list variable
children = tl children;
}
}
logging(
input: chan of string # communication channel named "input"
# that conveys 'strings'
) {
sys = load Sys Sys->PATH; # a variable that holds a reference to
# a module called Sys. Sys->PATH
# is a constant defined within that
# module indicating where it is
while (FOREVER) {
# text is a string (because it's type is derived from the
# rhs type -- which is "chan of string"
# It's value is assigned from the string fetched from the
# communication channel named "input"
text :=<- input;
# use the print() member of the module referenced by "sys"
# to print a string "somewhere" (i.e., like printf)
sys->print("%s\n", text)
}
}
job(surname: string,
children: list of (string, int) # you've seen this before...
) {
pipe: channel of string; # declare "pipe" to be a communication
# channel (should have been "chan") that
# conveys "string" data types.
# create a thread that executes the "logging" function (defined
# above). Pass it a communication channel that it will use to
# watch for incoming text
spawn logging(pipe);
# create a thread that executes the "greetings" function (defined
# above). Pass it the communication channel that it should use
# to interact with the "logging" function started above. Pass
# the surname and list of children's (names, ages) to that
# function (i.e., thread) so that it has some work to do.
spawn greetings(surname, children, pipe)
...
}
I.e., anything that doesn't say "chan" or "spawn" in the above
is "application" and unrelated to the tasking aspects of the
language.
