be06fc096a
better path going forward to handling upgrades. Old syntax files will stick around for compatibility purposes. Old syntax can be parsed into valid syntax trees via the old syntax (.peg) files, and then old syntax trees should be valid and can be upgraded via the normal code path. This change has lots of improvements to Nomsu codegen too.
368 lines
11 KiB
Plaintext
368 lines
11 KiB
Plaintext
#!/usr/bin/env nomsu -V1
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# How do I...
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# Write a comment? Put a # and go till the end of the line
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# How do I write a multi-line comment?
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After a comment line, any indented text
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is considered part of the comment
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(including any deeper-level indented text)
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The comment ends when the indentation ends
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# How do I import a file?
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use "core/control_flow.nom"
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# How do I import all the files in a directory?
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use "core"
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# How do I print stuff?
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say "Hello world!"
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# How do I set a variable?
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%foobar <- 1
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%text <- "Hello world"
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# Expressions that are more than just literal values require parentheses:
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%foobar <- (2 + 3)
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%one-two <- 12
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say %one-two
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# How do I modify a variable?
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%foobar <- (%foobar + 1)
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# Or, as a shorthand, you can do this to increment a variable:
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%foobar +<- 1
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# How do I define a mutli-line string?
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# In Nomsu, "strings" are called "text", and multi-line text looks like:
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%mutli-text <- ".."
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Start with "..", then put indented lines below it. The indented lines will not include
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the indentation, except when the lines are indented more than 4 spaces relative
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to the "..".
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<- E.g. the 2 spaces here will be included as part of the text.
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But this line will have no leading spaces.
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The text will continue until the indentation ends, skipping trailing newlines.
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# How do I put values inside text? (AKA string formatting, string interpolation)
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say ".."
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Text can contain a backslash followed by a variable, list, dict, or parenthesized
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expression. This escaped value will be converted to readable text, like so:
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The value of %foobar is \%foobar, isn't that nice?
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These are some numbers: \[1+1, 2+1, 3+1]
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The sum of 2 and 4 is \(2 + 4).
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A backslash not followed by any of these, and not at the end of a line
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like this: \ will just be treated as a backslash.
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Or, two backlashes will be treated as a single backslash, no matter what follows,
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like this: \\%foobar <- won't insert any values
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If you need to split a long line without inserting a newline, you can \
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..end a line with backslash and start the next line with two periods, like that.
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Similarly, you can put a long interpolated indented value like: \
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1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9
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.. between a backslash and two periods.
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say "Single-line text can contain escape sequences like \", \\, \n, \065, and \x0A"
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# How do I define a list?
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%my-list <- [1,2,"hello"]
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# Really long lists can use [..] followed by a bunch of indented values delimited
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by commas and/or newlines
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%my-really-long-list <- [..]
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1,2,3,4
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5,6
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7
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8,9,10
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# How do I use a list?
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%my-list <- ["first item", "second item", "third item"]
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# Lists are 1-indexed because they're implemented as Lua tables, so this prints "first item"
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say %my-list.1
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# List entries can be modified like this:
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%my-list.1 <- "ONE!!!"
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say (length of %my-list)
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# How do I define a dictionary/hash map?
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%my-dict <- {x: 99, y: 101}
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%my-dict <- {..}
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x: 101, y: 2
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"99 bottles": 99
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653: 292
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# How do I use a dict?
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# Dicts are also implemented as Lua tables, so they're accessed and modified the same way as lists
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say %my-dict.x
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%my-dict.x <- 9999
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# How do I do conditional branching?
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if: 1 < 10
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say "1 is indeed < 10"
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if: 1 > 10
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say "this won't print"
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..else
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say "this will print"
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# There's no "elseif", so for longer conditionals, a "when" branch is the best option
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when
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* (3 > 6)
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* (3 > 5)
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* (3 > 4)
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say "this won't print"
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* (3 > 3)
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say "this won't print"
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* (3 > 2)
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say "this will print"
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* else
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say "this is the default case"
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# How do I do a switch statement?
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when 3 = ?
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* 0
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* 1
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* 2
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say "this won't print"
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* 3
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say "this will print"
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* else
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say "this won't print"
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# How do I loop over a list (a foreach loop)?
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%list <- [1,2,3]
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for %x in %list
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say "For %x loop #\%x"
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# How do I loop over a number range?
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# This is inclusive, so it will loop over 1,2, and 3
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for %i in 1 to 3
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say "For %i in 1 to 3 loop #\%i"
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# This will print 0,2, and 4
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for %even in 0 to 5 by 2
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say "Even #\%even"
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for %backwards in 3 to 1 by -1
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say "Backwards #\%backwards"
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# How do I do a 'while' loop?
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%x <- 1
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repeat while: %x <= 3
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say "repeat while loop #\%x"
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%x +<- 1
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%x <- 1
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repeat until: %x > 3
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say "repeat until loop #\%x"
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%x +<- 1
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# How do I do an infinite loop?
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%x <- 1
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repeat
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say "repeat loop #\%x"
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%x +<- 1
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if: %x > 3
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stop repeating
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# How do I do a 'goto'?
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do
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%x <- 1
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=== %again ===
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say "GOTO loop #\%x"
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%x +<- 1
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if: %x <= 3
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go to %again
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say "finished going to"
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# How do I define a function/method/procedure?
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# In nomsu, they're called "action"s, and they can be declared like this:
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action [say both %first and also %second]
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say %first
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# Function arguments are accessed just like variables
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say %second
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# Actions can use "return" to return a value early
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action [first fibonacci above %n]
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%f1 <- 0
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%f2 <- 1
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repeat
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%tmp <- (%f1 + %f2)
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%f1 <- %f2
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%f2 <- %tmp
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if: %f2 > %n
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return %f2
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say (first fibonacci above 10)
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# Actions can have aliases, which may or may not have the arguments in different order
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action [..]
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I hate %worse-things more than %better-things
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I think %worse-things are worse than %better-things
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I like %better-things more than %worse-things
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..
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say "\(%better-things capitalized) rule and \%worse-things drool!"
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I like "dogs" more than "cats"
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I think "chihuahuas" are worse than "corgis"
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# Actions can have parts of the action's name spread throughout.
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Everything that's not a literal value is treated as part of the action's name
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say both "Hello" and also "again!"
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# Actions can even start with a parameter
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action [%what-she-said is what she said]
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say %what-she-said
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say "-- she said"
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"Howdy pardner" is what she said
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# The language only reserves []{}().,:;% as special characters, so actions
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can have really funky names!
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action [>> %foo-bar $$$^ --> % @& _~-^-~_~-^ %1 !]
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say %foo-bar
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say %
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say %1
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>> "wow" $$$^ --> "so flexible!" @& _~-^-~_~-^ "even numbers can be variables!" !
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# There's also full unicode support
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%こんにちは <- "こんにちは"
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action [% と言う]
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"\(%)世界"
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say (%こんにちは と言う)
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# Math and logic operations are just treated the same as actions in the syntax
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say (2 + 3)
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# So you can define your own operators, although they will need to be parenthesized to
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play nicely with other operators
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action [%a ++ %b]
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2 * (%a + %b)
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say (1 ++ (2 * 3))
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# How do I do grouping?
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# Expressions can be grouped by enclosing parentheses:
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say (2 + 3)
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# Or by an indented region
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say
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2 + 3
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# Or by ":" until the end of the line
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say: 2 + 3
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# If you need to keep going after an indented region, you can start the next line with ".."
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say both
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"Very long first argument that needs its own line"
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..and also "short second arg"
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action [my favorite number]: 21 + 2
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# This can be nested:
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say both
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my favorite
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..number
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..and also "foo"
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# Macros:
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# The "lua> %" and "=lua %" macros can be used to write raw lua code:
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action [say the time]
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lua> ".."
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io.write("The OS time is: "..os.time().."\n");
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say the time
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say "Math expression result is: \(=lua "(1 + 2*3 + 3*4)^2")"
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# Variables can be accessed via \%varname
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action [square root of %n]
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=lua "math.sqrt(\%n)"
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say "The square root of 2 is \(square root of 2)"
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# Macros can be defined to transform one bit of nomsu code into another using "parse % as %":
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parse [if %condition is untrue %body] as
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if (not %condition) %body
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# Or to transform nomsu code into custom lua code using "compile % to %"
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compile [if %condition on opposite day %body] to
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Lua ".."
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if not \(%condition as lua expr) then
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\(%body as lua statements)
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end
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# Constants can be defined as macros
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parse [TWENTY] as: 20
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# When they're invoked, they'll need parentheses just like a function call
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parse [TWENTY ONE] as: 21
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# If you need to use compile-time actions in the same file that they're defined in, you
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can add a line of tildes (3 or more), and the file will be split into chunks, and each
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chunk will run before the next one compiles. (note that each chunk has its own scope)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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if (1 > (TWENTY)) is untrue
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say "Nomsu parsing macros work!"
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say "It looks like a keyword, but there's no magic here!"
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if (1 > (TWENTY)) on opposite day
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say "Lua compiling macros work!"
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say "It looks like a keyword, but there's no magic here!"
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# How do I use an action as a value?
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# Well... it's always *possible* to fall back to Lua behavior for something like this:
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action [best of %items according to %key-fn]
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<- {%best:nil, %best-key:nil}
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for %item in %items
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%key <- (=lua "\%key-fn(\%item)")
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if: (%best is (nil)) or (%key > %best-key)
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<- {%best:%item, %best-key:%key}
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return %best
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say: best of [2,-3,4,-8] according to ([%x] -> (%x * %x))
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# But nomsu was mostly designed so that you don't *need* to. Instead of creating a
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one-off function to pass to another function and get called a bunch of times, you
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could use a macro to generate a single block of code that inlines the expression you
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want to use:
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parse [best of %items where %item-var has score %key-expr] as
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result of
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<- {%best:nil, %best-key:nil}
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for %item-var in %items
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%key <- %key-expr
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if: (%best is (nil)) or (%key > %best-key)
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<- {%best:%item-var, %best-key:%key}
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return %best
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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say: best of [2,-3,4,-8] where %x has score (%x * %x)
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# The first example generates code that looks like:
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A_best_of_1_according_to_2 = function(items, key_fn)
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local best, best_key = nil, nil
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for _, item in ipairs(items) do
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local key = key_fn(item)
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if best == nil or key > best_key then
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best, best_key = item, key
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end
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end
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return best
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end
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print(A_best_of_1_according_to_2({2,-3,4,-8}, function(x)
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return x * x
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end))
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But the second example produces something more like:
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print((function()
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local best, best_key = nil, nil
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for _, x in ipairs({1,-2,3,-4}) do
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local key = x * x
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if best == nil or key > best_key then
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best, best_key = x, key
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end
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end
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return best
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end)())
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Notice that the second example has inlined the key function, so that in the inner loop,
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the code only has to do a multiplication, instead of calling a function that does the
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multiplication. In addition to being more efficient, it's also more powerful and
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flexible for the language to allow you to define syntax that manipulates expressions.
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