# HG changeset patch
# User IBBoard <dev@ibboard.co.uk>
# Date 1505246331 -3600
# Node ID 86668d32e1629b0f4404f4c50b14aa9fb42c8a21
# Parent  15eb99e79dd4a7b3a7cb509ead61797e1046f8b2
Add Day 2 code

diff -r 15eb99e79dd4 -r 86668d32e162 2-Io/day2-conditionals.io
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/2-Io/day2-conditionals.io	Tue Sep 12 20:58:51 2017 +0100
@@ -0,0 +1,7 @@
+# IF blocks are functions
+if(true, "It is true", "It is false") println
+if(false, "It is true", "It is false") println
+# Or there's a more conventional long-hand, but it doesn't behave quite
+# the same because we can't "println" the result - we'd need to put it
+# inside the "then" and "else" functions
+if(true) then("It is true") else ("It is false") #println
\ No newline at end of file
diff -r 15eb99e79dd4 -r 86668d32e162 2-Io/day2-loops.io
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/2-Io/day2-loops.io	Tue Sep 12 20:58:51 2017 +0100
@@ -0,0 +1,30 @@
+# loop() gives an infinite loop - let's not run that!
+
+# While loops aren't too unfamiliar:
+#     while(condition, code)
+# where calls can be put in a "block" with semicolons
+i := 1
+# Notice the lack of "++"
+while(i <= 11, i println; i = i + 1); "This one goes up to 11" println
+"Or we could have put the line here" println
+
+# For loops are similarly simple:
+#    for(variable, min, max, code)
+for(i, 1, 11, i println); "For this one also goes up to 11" println
+
+# Oddly (but necessarily) the increment is in the middle of that as an optional parameter
+increment := 2
+for(i, 1, 11, increment, i println); "For this one goes to 11 in 2s" println
+
+# This is bad in some cases, because Io accepts extra args without complaining
+# BUT it'll fill in extra args first
+# AND things have potentially unexpected return values (e.g. "11 println" returns 11)
+# Although it's actually just returning *something* so that you can chain more methods
+# and in many cases then "self" is the best return, e.g. "11 println println" prints twice
+for (i, 1, 10, 2, i println, "extra arg gets ignored")
+"Bad arg example" println
+for (i, 1, 10, /* no increment arg, so command runs *and* becomes increment*/ i println, "extra arg becomes message")
+# However, we apparently only see the last print! Seems odd and unexpected - unless we're taking it from the previous call?
+for (j, 1, 10, /* no increment arg, so command runs *and* becomes increment*/ j println, "extra arg becomes message")
+# Yep, this crashes out!
+
diff -r 15eb99e79dd4 -r 86668d32e162 2-Io/day2-messages.io
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/2-Io/day2-messages.io	Tue Sep 12 20:58:51 2017 +0100
@@ -0,0 +1,33 @@
+# Everything is a message in Io, apparently. Everything.
+# Messages have senders, receivers and args, and you can get and use those objects.
+# So the example makes a post office.
+postOffice := Object clone
+# Add a method that returns the sender object
+postOffice packageSender := method(call sender)
+"Post office: " print
+postOffice println
+mailer := Object clone
+# Call the PostOffice's method
+mailer deliver := method(postOffice packageSender)
+"Mailer: " print
+mailer println
+# Calling the method returns the caller (sender via the postOffice object)
+mailer deliver println
+
+# We can also get message arguments and name
+# Let's do this a little differently to the book!
+postOffice messageDetails := method(call message name println; call message arguments println)
+postOffice messageDetails("One", 2, :three)
+
+# Because of how args are passed unevaluated then we can make our own "unless" method
+unless := method(
+    (call sender doMessage(call message argAt(0))) \
+        ifFalse(call sender doMessage(call message argAt(1))) \
+        ifTrue(call sender doMessage(call message argAt(2)))
+)
+# Note the line continuations - this seems more readable than the approach in the book of
+# leaving the "ifFalse(" and "ifTrue(" on the previous line!
+# Also, this is an IF in the form "[boolean statement] ifFalse(code) ifTrue(code)", not the earlier
+# "if(boolean, true-code, false-code)" form
+
+unless (1 == 2, write("One is not two\n"), write("OMG! Maths has broken!!!!\n"))
\ No newline at end of file
diff -r 15eb99e79dd4 -r 86668d32e162 2-Io/day2-operators.io
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/2-Io/day2-operators.io	Tue Sep 12 20:58:51 2017 +0100
@@ -0,0 +1,21 @@
+# Operators are syntactic sugar and can be listed from a table:
+OperatorTable println
+
+# Creating an operator involves defining it with a precedence
+# (index based on the output from the previous table)
+OperatorTable addOperator("xor", 11)
+
+# And then implementing it on appropriate prototypes
+# Note that Io is open-edit, like Ruby, so we can screw with core stuff
+# like Booleans and extend them
+true xor := method(bool, if(bool, false, true))
+false xor := method(bool, if(bool, true, false))
+
+# For some reason I have to work out, the prints don't work here
+# They print the second value. But running in REPL works and return correct
+# value (before printing wrong one)
+(true xor true) println
+(true xor false) println
+(false xor true) println
+(false xor false) println
+