nomsu/examples/tutorial.nom

# One liner comments start with # and go till end of line
#.. Multi-line comments start with #.. and
    continue until dedent

# Import files like so:
require "lib/core.nom"

# Numbers:
23
4.5
#.. Since this language cross-compiles to lua, integers and floating point numbers are
    both represented using the same primitive.

# Strings:
"asdf"
".."|This is a multi-line string
    |that starts with ".." and includes each indented line that starts with a "|"
    |until the indentation ends

# Lists:
[1,2,3]
[..]
    "like multi-line strings, lists have an indented form", "that can use commas too"
    "or just newlines to separate items"
    5
    6,7,8

# Dictionaries (AKA hash maps):
dict [["x", 99], ["y", 101]]
dict [..]
    ["z", 222]
    [383, "howdy"]

# Function calls:
say "Hello world!"

# Variables use the % sign:
%str =: "Hello again"
say %str

# There are +=:, -=:, *=:, /=:, ^=:, and=:, or=:, and mod=: operators for updating variables
%x =: 1
%x +=: 100
say %x

# Conditionals look like this:
if (1 < 10):
    say "1 is indeed < 10"

if (1 > 10):
    say "this won't print"
..else:
    say "this will print"

# For longer conditionals, a "when" branch is the best option
when:
    ? 1 > 4:
        say "this won't print"
    ? 1 > 3:
        say "this won't print"
    ? 1 > 2:
        say "this won't print"
    ?:
        say "this will print"

# When "when" is given an argument, it works like a switch statement
when 3:
    == 1:
        say "this won't print"
    == 2:
        say "this won't print"
    == 3:
        say "this will print"
    ==:
        say "this won't print"

# Loops look like this:
for %x in [1,2,3]:
    say ".."|for loop over list #\%x\

# If you want to iterate over a numeric range, you can use some built in functions like this:
for %x in (1 through 3):
    say ".."|for loop over number range #\%x\

# While loops:
%x =: 1
repeat while (%x <= 3):
    say ".."|repeat while loop #\%x\
    %x +=: 1

%x =: 1
repeat until (%x > 3):
    say ".."|repeat until loop #\%x\
    %x +=: 1

# Infinite loop:
%x =: 1
repeat:
    say ".."|repeat loop #\%x\
    %x +=: 1
    if (%x > 3):
        break

# GOTOs:
do:
    %x =: 1
    -> %again
    say ".."|go to loop #\%x\
    %x +=: 1
    if (%x <= 3):
        go to %again
    say "finished going to"


# Function definition:
rule [say both %first and also %second] =:
    say %first
    # Function arguments are accessed just like variables
    say %second

# The last line of a function is the return value
rule [add %x and %y] =:
    %result =: %x + %y
    %result

# Functions can use "return" to return a value early
rule [first fibonacci above %n] =:
    %f1 =: 0
    %f2 =: 1
    repeat:
        %tmp =: %f1 + %f2
        %f1 =: %f2
        %f2 =: %tmp
        if (%f2 > %n):
            return: %f2

say (first fibonacci above 10)

# Functions can have aliases, which may or may not have the arguments in different order
rule [..]
    I hate %worse-things more than %better-things
    I think %worse-things are worse than %better-things
    I like %better-things more than %worse-things
..=:
    say ".."|\%better-things capitalized\ rule and \%worse-things\ drool!

I like "dogs" more than "cats"
I think "chihuahuas" are worse than "corgis"


#.. Function calls can have parts of the function's name spread throughout.
    Everything that's not a literal value is treated as part of the function's name
say both "Hello" and also "again!"

# Functions can even have their name at the end:
rule [%what-she-said is what she said] =:
    say %what-she-said
    say "-- she said"

"Howdy pardner" is what she said

#.. The language only reserves []{}().,:;% as special characters, so functions and variables
    can have really funky names!
rule [>> %foo-bar$$$^ --> %@@& _~-^-~_~-^ %1 !] =:
    say %foo-bar$$$^
    say %@@&
    say %1

>> "wow" --> "so flexible!" _~-^-~_~-^ "even numbers can be variables!" !

# Math and logic operations are just treated the same as function calls in the syntax
say (2 + 3)
# So it's easy to define your own operators
rule [%a ++ %b] =:
    2 * (%a + %b)

say (2 ++ 3)


#.. Code blocks start with ":" and either continue until the end of the line
    or are indented blocks

# One liner:
: say "hi"

# Block version:
:
    say "one"
    say "two"

#.. So the function definitions above are actually just passing a regular string, like
    "say both %first and also %second", and a code block to a function called "rule % %"
    that takes two arguments.

# Line continuations work by starting the next line with ".."
say both "Bruce"
..and also "Lee"

# This can be combined with the block forms of literals:
say both ".."
    |Four score and seven years ago our fathers brought forth, upon this continent,
    |a new nation, conceived in liberty, and dedicated to the proposition that
    |"all men are created equal"
..and also "-- Abraham Lincoln"

rule [my favorite number] =: 21 + 2

# Subexpressions are wrapped in parentheses:
say (my favorite number)
# There's a multi-line indented block form for subexpressions too:
say (..)
    my favorite
    ..number

# Block strings can interpolate values by enclosing an expression in a pair of \s
say ".."|My favorite number is \my favorite number\!

say ".."
    |My favorite number is still \(..)
        my favorite
        ..number
    ..\, but this time it uses an indented subexpression!

rule [sing %starting-bottles bottles of beer] =:
    for %n in (%starting-bottles down through 0):
        say ".."
            |\%n if (%n > 0) else "No more"\ \"bottle" if (%n == 1) else "bottles"\ of beer on the wall.
            |\"" if (%n == 0) else "    Take one down, pass it around..."\

sing 9 bottles of beer

#.. Note that because math and logic operations are just macros, they require a lot
    of parentheses to disambiguate. There's no PEMDAS.
say (5 + (4 * (- (1 + (6 + 2)))))
# For convenience, +,*,"and", and "or" have been hand defined to work with up to 4 operands: 
1 + 2 + 3 + 4
say "Done with math."
1 * 2 * 3 * 4
1 and 2 and 3 and 4
1 or 2 or 3 or 4
# Longer lists can use "sum of %", "product of %", "all of %", and "any of %", respectively, or lots of parentheses. 
sum of [1,2,3,4,5,6,7]
product of [1,2,3,4,5,6,7]
all of [1,1,1,1,0,1,1]
any of [0,0,0,0,1,0,0]
# And 3-operand chained inequality comparisons have been defined: 
1 < 2 <= 3

say "Done with math."


# Macros: 
# The "lua block %" and "lua expr %" macros can be used to write raw lua code: 
rule [say the time] =:
    lua block ".."
        |io.write("The OS time is: ")
        |io.write(tostring(os.time()).."\\n")
say the time
say ".."|Math expression result is: \lua expr "(1 + 2*3 + 3*4)^2"\

#.. In the lua environment, "vars" can be used to get local variables/function args, and
    "compiler" can be used to access the compiler, function defs, and other things
rule [square root of %n] =:
    lua expr "math.sqrt(vars.n)"
say ".."|The square root of 2 is \square root of 2\

# Macros can be defined as functions that take unprocessed syntax trees and return lua code 
# "macro block %" is for defining macros that produce blocks of code, not values 
macro block [unless %condition %body] =: ".."
    |if not (\%condition as lua\) then
    |    \(lua expr "vars.body.value") as lua\
    |end

unless (1 > 10):
    say "Macros work!"
    say "It looks like a keyword, but there's no magic here!"

# and "macro %" is for defining macros that produce an expression 
macro [%value as a boolean] =: ".."
    |(not not (\%value as lua\))
macro [yep] =: "true"