Add rubyish example

Ruby subset extended from the `rubyish-4` example, as introduced in the Edument [Rakudo and NQP internals course](https://github.com/edumentab/rakudo-and-nqp-internals-course).
Raku · Oct 14, 2013 · 3c7ac10 · 3c7ac10
1 parent 246aaae
commit 3c7ac10
Show file tree

Hide file tree

Showing 18 changed files with 1,184 additions and 0 deletions.
diff --git a/examples/rubyish/README.md b/examples/rubyish/README.md
@@ -0,0 +1,80 @@
+nqp-rubyish
+===========
+
+Ruby subset extended from the `rubyish-4` example, as introduced in the Edument
+[Rakudo and NQP internals course](https://github.com/edumentab/rakudo-and-nqp-internals-course).
+
+Example usage:
+```
+    % nqp rubyish.nqp -e'puts "Hello World!"'
+    % nqp rubyish.nqp rubyish-examples/green-bottles.rbi
+    % nqp rubyish.nqp  # repl mode
+    > puts 37 + 5
+```
+Features:
+- simple strings 'Hello World!' %q{...}
+- interpolating strings: "number #{37+5}" %Q{Hello #{planet}!}
+- quoted words: `%w[aa bb cc]` 
+- scoping, including $globals, @class_instance and @@package variables
+- conditional blocks: if ... then ... elsif ... else ... endif
+- begin .. end blocks
+- nqp opcode calls
+- a few built-ins: abort, print, puts, sleep
+- infixish assigments: += -= *= ...
+- very simple classes and objects with attributes. no inheritence yet
+- while and until loops
+- statement modifiers `if` `unless`, `while`,  `until` e.g.: `puts 42 if `
+- basic arrays and hashes
+- for loops on arrays: `for val in [10,20,30] do puts val end`
+- for loops on hash keys: `h = {'a'=>10, 'b'=>20}; for k in h do puts h{k} end`
+- lightweight eRuby like templating, see [green-bottles.rbi](rubyish-examples/green-bottles.rbi)
+
+Notes:
+
+Handy Options:
+
+    % nqp rubyish.nqp --target=parse -e'puts "Hello World!"'  # dump parse
+    % nqp rubyish.nqp --target=ast   -e'puts "Hello World!"'  # dump ast
+
+To run tests:
+```
+    % prove -v -e'nqp rubyish.nqp' t
+```
+
+Expressions are Perlish rather than Rubyish:
+
+- `+` always does addition (doesn't concatenate strings)
+- `~` has been introduced as the concatenation operator
+- `>`, `==`, `<=` ... only do arithmetic comparisons
+- `gt`, `eq`, `le` ... do string comparisions
+- 0, '0', ''  are false in a boolean context.
+- hash dereferencing is via angle braces: `price = fruit<apples>` or
+curly brackets `puts fruit{'bannanas'}`
+
+- nqp op-codes can be called like regular functions. E.g.
+```
+    puts nqp::if(2+2 == 4, 'yup', 'nope' )
+```
+- this includes nqp control-flow functions:
+```
+    n = 99
+    nqp::while n > 0, begin
+        puts "#{n} green bottles standing on the wall"
+        puts "#{n} green bottles standing on the wall"
+        puts "and if one green bottle should accidently fall..."
+        nqp::sleep 1
+        n -= 1
+        puts "there'd be #{n} green bottles standing on the wall"
+        nqp::sleep 2
+    end
+```
+There's some context sensitive parsing to distinguish functions and
+expressions, E.g.
+```
+   yy = 37
+   puts yy -5   # parsed as an expression; output is 32
+
+   def xx(n) ; 37 - n; end
+   puts xx -5   # parsed as a method call; output is 42
+```
+
diff --git a/examples/rubyish/rubyish-examples/green-bottles.rbi b/examples/rubyish/rubyish-examples/green-bottles.rbi
@@ -0,0 +1,31 @@
+# eRubyish templating - see http://en.wikipedia.org/wiki/ERuby
+# There are only three directives:
+# <%rbi>    - Header; remainder of the source file is the template body
+# <% ... %> - rubyish statements
+# #{ ... }  - inserted content
+
+# Any arbritrary code can appear before the template. Output to stdout
+# is appended to the template, both before and within the template body
+
+puts '<?xml>'
+
+<%rbi>
+<html>
+    <body>
+        <h1>Green Bottles...</h1>
+        <%n = 12      %>
+        <%while n > 0 %>
+            <blockquote>
+                <em>#{n}</em> green bottles standing on the wall,
+                <em>#{n}</em> green bottles standing on the wall
+                <br/>
+                <%# -- gratuitous use of puts ------------------------------ %>
+                <%puts %q{and if one green bottle should accidently fall...} %>
+                <br/>
+                <%n -= 1 %>
+                there'd be <em> #{if n then n else 'no' end} </em> green bottles standing on the wall
+            </blockquote>
+        <%end%>
+    </body>
+</html>
+
diff --git a/examples/rubyish/rubyish-examples/pi.rbi b/examples/rubyish/rubyish-examples/pi.rbi
@@ -0,0 +1,23 @@
+# naive approximation: pi = 4 * (1 - /1/3 + 1/5 ...)
+
+limit = 2500000
+def time ; nqp::time_i() ; end
+
+n = 1;
+pi_over_4 = 0.0
+
+print 'hang on a few moments...'
+start_time = time()
+
+while n < limit do
+
+  m = 4.0*n - 1.0
+  pi_over_4 += 1/(m - 2) - 1/m
+  n += 1
+
+end
+
+puts "(completed #{limit} iterations in #{time() - start_time} sec )"
+
+pi = pi_over_4 * 4
+puts pi