updates

[ocean-D] / Ocean-functions

diff --git a/Ocean-functions b/Ocean-functions
index 9014d1adc9b26d9d057c3d6d9361046db713acc8..50834001635905cb15e345b353f972f39ea1f280 100644 (file)
--- a/Ocean-functions
+++ b/Ocean-functions
@@ -1,8 +1,9 @@
-I want to add functions and procedures soon.  I should decide on syntax at least.
+I want to add functions and procedures soon.  I should decide on syntax
+at least.

 
 

-The args to a function are effective a struct, so I want it to look the same.
-C doesn't allow "int a, b, c" in the parameters, which I think is clumsy.
-struct can be
+The args to a function are effectively a struct, so I want it to look
+the same.  C doesn't allow "int a, b, c" in the parameters, which I
+think is clumsy.  struct can be

 
   struct name:
      a,b,c:number
 
   struct name:
      a,b,c:number


@@ -13,7 +14,7 @@ So function might be
    func name:
        arg1, arg2: type
        arg3: type2
    func name:
        arg1, arg2: type
        arg3: type2

-   returns type
+   return type

    do:
        stuff
 
    do:
        stuff
 


@@ -22,16 +23,82 @@ it has a return structure.  So many C functions have 'ret' or 'result'
 variable that it might be nice to follow the Pascal approach of
 assigning to the function name??  or having
 
 variable that it might be nice to follow the Pascal approach of
 assigning to the function name??  or having
 

-    func name:
+    func name

        args:types
        args:types

-    returns:
+    return

        results:types
        results:types

-    do:
+    do

        statements
 
 A shorter version would be
 
     func name(args:types;args:types):type { }
 or
        statements
 
 A shorter version would be
 
     func name(args:types;args:types):type { }
 or

-    proc name(args:types;args:types):(result:type;...) {}
+    func name(args:types;args:types):(result:type;...) {}

 
 

+
+Can arguments be optional?
+ - yes, if "= value" follows the type
+Can we have variable number of args
+ - yes. Any arg can be an inline-array. The last arg can
+   have undefined length [].
+Can named args be passed in
+ - yes, once I have a syntax for manifest structs
+   
+Arrays seem very different from structs.
+ - they don't have names (as types)
+ - they don't need grouping in function params??
+Does this make any sense?
+Maybe I should require the grouping
+  printf("%d %d %d", (1,2,3))
+??
+
+
+Functions can be used before being declared - analysis happens after all is read.
+
+'main' is given an array of strings of unknown length.
+So I need the formal parameter to accept variable-length arrays.
+Do I use
+   argv:[] string
+and support "argv.len", or do I use
+   argv:[argc] string
+which instantiates argc with the length?
+Probably the latter.
+
+Arrays have to be passed by reference, they are const if :: used for type.
+Structs .. ditto.
+Strings and numbers are immutable.
+
+So I need functions to turn strings into number or bool.
+Just bool() and number() for now.
+So
+DONE 1/ change 'program' to make everything a string, and use functions to get numbers.
+DONE 2/ change 'program' to receive an array with bindably size
+DONE 3/ change 'program' to 'func main' etc
+DONE4/ allow more functions.
+
+What syntax to use for formal types?
+I will need type parameterisation some day.  For now I just need the
+size of an array to be parameterised.
+  argv:[argc]string
+looks like normal type.  But it isn't clear if argc is a global constant
+or a variable.
+  argv:[argc:int]string
+seem redunant because of course the array index is an int.
+  argv:[argc:]string
+might be acceptable.
+It is like leaving out the type is
+   a := 4
+
+So let's go with that.
+
+
+DONE To handle functions, and recursion in particular, I need a concept of a
+stack frame in the interpreter.  This needs to include room for
+parameters and results and local variables.  So a function needs to know
+the size of its frame, and each variable needs an offset.
+So I need to switch 'program' over to this approach before adding
+functions.
+Then the function frame will have a results frame separate from the
+main frame, as it can last longer.  So each variable needs to be marked
+as 'result' or not.