hello world in L3

1 Say hello

Start the gui via

l3gui

and paste the code

print "hello world!"

(via the middle mouse button on the canvas) to get

Running this via right button > run code, we get

hello world!
(None, 3)

on the console. (None, 3) is simply the (value, timestamp) returned by print.

2 Second run

Run it again and get only

(None, 3)

Because the print command is unchanged it is not executed again and the old value is returned.

3 Many hellos

When there is more than one world, using

for num in range(5):
    print "hello world %d" % num

is better.

The first run of

gives

hello world 0
hello world 1
hello world 2
hello world 3
hello world 4
(None, 201)

with repeated runs just returning

(None, 201)

4 Many hellos, reused

These values are just the ones we want to use in the greeting template

print_(
    "<value>")

instead of <value>, so we retrieve them via the menu selection

to get

and insert that list into the template. This is what the new hello looks like:

Running this, we get

['hello world 0', 'hello world 1', 'hello world 2', 'hello world 3', 'hello world 4']
(None, 225)

Running it again just gives the value

(None, 225)

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