"static", more docs, indenting, fix set

README.md

@@ -7,11 +7,11 @@ Idk, seemed cool
 ## Usage
 At the top of your file, include the following:
 ```fennel
-(import-macros {: def : q : ttype} :terra)
+(import-macros {: def : q : ttype : static} :terra)
 ```
 The `def` macro defines a new terra function. The `q` macro defines a quoted terra expression.
 The `ttype` macro allows you to specify terra type definitions that can't be expressed with 
-regular lua syntax.
+regular lua syntax. The `static` macro allows you to define "global" terra variables.
 
 Notably, all of these macros return values, and none of them define new variables, local or global.
 I could maybe be persuaded to make `def` work like `fn` and optionally define a local, but for now,
@@ -29,6 +29,12 @@ Simple example:
 ```fennel
 (local add (def [x int y int : int]
     (return (+ x y))))
+
+; compiles to:
+; local add = terra(x : int, y : int) : {int}
+;   return (x + y)
+; end
+
 (add 1 2) ; returns 3
 ```
 
@@ -38,19 +44,114 @@ Unlike Fennel, we do not implement implicit return semantics, and early returns
 Sorry Phil.
 
 ### q
-Defines a terra quotation, compiling down to the `\`` operator if given one argument, and
+Defines a terra quotation, compiling down to the ` `` ` operator if given one argument, and
 `quote` / `end` if given more than one.
 
-### syntax within `def` and `q` forms
+```fennel
+(fn inc [x] (q (+ x 1))) ; compiles to: function(x) `(x + 1) end
+
+```
+
+### Type syntax
+In Terra, types are Lua values and can be constructed from regular Lua code, outside of
+`terra` or `quote` blocks. (There are certain places inside these blocks where types can
+be constructed as well.) However, because Terra significantly extends the syntax of Lua to 
+allow for convenient type construction, Garden also must provide a mini-language to support 
+it.
+
+Inside `terra` or `quote` blocks, whenever you have a form that requires a type to be passed
+to it, the compiler will automatically enter a type-compiling context. Outside of these blocks,
+the `ttype` macro can be used.
+
+#### Pointers and arrays
+Pointers to types and arrays of types use the Fennel "sequence table" syntax. Alternatively, 
+the `&` operator can be used.
+```fennel
+(local intptr (ttype [int]))      ; compiles to: &int
+(local intptr2 (ttype (& int)))   ; also compiles to: &int
+(local intarray (ttype [int 16])) ; compiles to: int[16]
+```
+
+#### Structs
+Structs are defined using the Fennel "key-value table" syntax. For each row in the table,
+the keys are Fennel symbols representing the name of the field, and the values are type 
+expressions. If, instead of a symbol, the compiler finds the string `:union`, the value
+is expected to be another "key-value table" containing the same structure. Struct definitons
+can be nested.
+
+Note that the field names must be valid Lua symbols; no name-mangling is done. Might be
+worth doing that at some point; it seems likely that I will be annoyed if we don't
+auto-convert `-` to `_` at least.
 
 ```fennel
-(var name initial-value)
+(local Variant (ttype {tag int
-(var name type initial-value)
+                       :union {number float
+                               string [int8]
+                               complex {real float imag float}}}))
+; compiles to:
+; local Variant = struct {
+;   tag : int,
+;   union {                               
+;     number : float,
+;     string : &int8,
+;     complex : struct {
+;       real : float,
+;       imag : float
+;     }
+;   }  
+; }
+```
+
+#### Function pointers
+Function pointer types are defined with the `->` form, which accepts two arguments - a sequence
+of types representing the input parameter types, and a sequence of types representing the return
+value. Actually this kind of sucks, I think we should use the same syntax as `def`. I'll probably
+change this. But this is how it works right now:
+
+```fennel
+(local callback (ttype (-> [[int] int] [int]))) ; compiles to: local callback = { &int, int } -> { int }
+```
+
+#### Tuples
+Tuple types are defined in Terra with a generic Lua function call to `tuple` that takes a variable
+number of types as parameters. This is supported directly, like any type declaration consisting of
+a function call, but there is a shortened form using `$` to match the tuple instantiation syntax.
+
+```fennel
+(ttype (tuple int [int])) ; compiles to: tuple(int, &int)
+(ttype ($ int [int]))     ; compiles to: tuple(int, &int)
+```
+
+#### Escaping
+Arbitrary Fennel expressions can be evaluated in a type-compilation context using Fennel's `,` prefix,
+which is normally used by macros. If you need to re-enter a type-compilation context after escaping,
+you'll need to nest a call to `ttype`. (I'm considering using ` `` ` for this purpose, but I might have
+it consistently mean "create a quote" everywhere. Not sure.)
+
+```fennel
+(ttype ($ [int] (fn-accepting-type [int]) ,(fn-accepting-seq [5]) (fn-accepting-seq-of-types ,[(ttype [int])])))
+; compiles to:
+; tuple(&int, fn_accepting_type(&int), fn_accepting_seq({ 5 }), fn_accepting_seq_of_types({ &int }))
+```
+
+### Terra syntax
+
+#### var
+```fennel
+(var name initial-value) ; compiles to:      var name = initial-value
+(var name type initial-value) ; compiles to: var name : type = initial-value
 ```
 Define a local variable named `var`, and set its initial value to `initial-value`. You can
 manually specify a `type`, or you can let terra infer it from `initial-value`. There is no
 syntax for _not_ initalizing the variable on declaration.
 
-```fennel
+#### Pointers and arrays
+Dereferencing a pointer or accessing an element in an array uses the same syntax as defining a pointer 
+or array type - the Fennel sequence literal. To take a reference to a value, you can use the `&` form.
 
+```fennel
+(def [ptr [int]] (return [ptr]))             ; compiles to: terra (ptr : &int) return @ptr end
+(def [arr [int 8]] (return [arr 5]))         ; compiles to: terra (arr : int[8]) return arr[5] end
+(def [nested [[int]]] (return [nested 0 3])) ; compiles to: terra (nested : &&int) return nested[0][3] end
+(def [])
 ```

go.fnl

@@ -1,15 +1,23 @@
 (local fennel (require :fennel))
-(import-macros {: terra : unterra : untype : def : q : ttype} :terra)
+(import-macros {: def : q : ttype : static : unterra : untype} :terra)
+
+(local N (static int 5))
+(print N)
+(fn inc [x] 
+  (print "calling inc" x)
+  (q (+ ,x 1)))
 
-(local N 5)
-(fn inc [x] (q (+ ,x 1)))
 (print (unterra
-    (def [x int] 
+    (def [x int]
-        (return ,(inc `x)))))
+        (set N (+ N x))
+        (return N))))
 
-(print 
+(local addN (def [x int]
-    (def [x int] 
+        (set N (+ N x))
-        (return ,(inc `x))))
+        (return N)))
+
+(print addN)
+(print (N:get) (addN 3) (N:get))
 
 ; (local inc (def [x [int]] (return [x N])))
 ; (print (inc 5))

terra.fnl

@@ -12,6 +12,15 @@
 (fn kvcommasep [tbl f ?sep]
     (commasep (. (getmetatable tbl) :keys) #(f $1 (. tbl $1)) ?sep))
 
+(fn indent [str scope]
+    (.. (string.rep " " scope.indent) str))
+
+(fn block [pre stmts post scope f]
+    (set scope.indent (+ scope.indent 2))
+    (local block (commasep stmts #(indent (f $1) scope) "\n"))
+    (set scope.indent (- scope.indent 2))
+    (.. pre "\n" block "\n" (indent post scope)))
+
 (local extract {})
 (fn extract.quotes-in-table [into tbl inputs locals]
     (collect [k v (pairs tbl) &into into] k (extract.quotes v inputs locals)))
@@ -40,8 +49,14 @@
     {:locals {}
      :env {}
      :input []
+     :indent 0
      :push (fn [self] (set self.locals (setmetatable {} {:__index self.locals})))
      :pop (fn [self] (set self.locals (. (getmetatable self.locals) :__index)))
+     :with (fn [self f]
+             (self:push)
+             (local result (f))
+             (self:pop)
+             result)
      :expr (fn [self expr]
              (if (and (sym? expr) (not (multi-sym? expr))) (self:env-ref expr)
                  (= (type expr) :number)                   (tostring expr)
@@ -55,22 +70,22 @@
                     (table.insert self.input {: name : expr})
                     ref)))
      :env-ref (fn [self symbol]
-        (let [name (tostring symbol)
+                (let [name (tostring symbol)
-              loc (. self.env name)]
+                    loc (. self.env name)]
-            (if loc loc
+                    (if loc loc
-                (let [envloc (safesym name)]
+                        (let [envloc (safesym name)]
-                    (tset self.env name envloc)
+                            (tset self.env name envloc)
-                    (table.insert self.input {:name envloc :expr (sym name)})
+                            (table.insert self.input {:name envloc :expr (sym name)})
-                    envloc))))
+                            envloc))))
      :reference (fn [self symbol]
-        (let [name (tostring symbol)
+                    (let [name (tostring symbol)
-              loc (. self.locals name)]
+                        loc (. self.locals name)]
-            (if loc loc (self:env-ref symbol))))
+                        (if loc loc (self:env-ref symbol))))
      :addlocal (fn [self symbol]
-        (let [name (tostring symbol)
+                 (let [name (tostring symbol)
-              loc (safesym name)]
+                    loc (safesym name)]
-            (tset self.locals name loc)
+                    (tset self.locals name loc)
-            loc))})
+                    loc))})
 
 (local comp {})
 (local forms {})
@@ -150,10 +165,7 @@
         [name initval] (.. "var " (scope:addlocal name) " = " (comp.expr initval scope))))
 
 (fn forms.do [stmts scope]
-    (scope:push)
+    (scope:with #(block :do stmts :end scope #(comp.expr $1 scope))))
-    (local lines (icollect [_ stmt (ipairs stmts)] (comp.expr stmt scope)))
-    (scope:pop)
-    (table.concat lines "\n"))
 
 (fn find-ival [tbl pred]
     (var ival nil)
@@ -162,17 +174,14 @@
     ival)
 
 (fn forms.def [[arglist & stmts] scope]
-    (scope:push)
+    (scope:with #(let [iarg-return-sep (find-ival arglist #(and (sym? $1) (= (tostring $1) ":")))
-    (let [iarg-return-sep (find-ival arglist #(and (sym? $1) (= (tostring $1) ":")))
+                       argpairs (fcollect [i 1 (length arglist) 2 &until (= i iarg-return-sep)] 
-          argpairs (fcollect [i 1 (length arglist) 2 &until (= i iarg-return-sep)] 
+                                    {:name (. arglist i) :type (. arglist (+ i 1))})
-                        {:name (. arglist i) :type (. arglist (+ i 1))})
+                       rettyps (when iarg-return-sep (icollect [i typ (ipairs arglist)] (when (> i iarg-return-sep) typ)))
-          rettyps (when iarg-return-sep (icollect [i typ (ipairs arglist)] (when (> i iarg-return-sep) typ)))
+                       rettyp  (if rettyps (.. ": { " (commasep rettyps #(comp.type $1 scope)) " }") "")
-          rettyp  (if rettyps (.. ": { " (commasep rettyps #(comp.type $1 scope)) " }") "")
+                       argdefs (commasep argpairs #(.. (scope:addlocal $1.name) " : " (comp.type $1.type scope)))]
-          argdefs (commasep argpairs #(.. (scope:addlocal $1.name) " : " (comp.type $1.type scope)))
+                    (block (.. "terra (" argdefs ")" rettyp) stmts :end scope #(comp.expr $1 scope)))))
-          fulldef (.. "terra (" argdefs ")" rettyp "\n" (forms.do stmts scope) "\nend")]
+
-        (scope:pop)
-        fulldef))
-(fn forms.predef [fntyp scope] (.. ))
 (fn forms.return [[expr] scope] (.. "return " (comp.expr expr scope)))
 (fn forms.cast [[typ expr] scope]
     (.. "([" (comp.type typ scope)"](" (comp.expr expr scope) "))"))
@@ -188,11 +197,16 @@
     (def-infix op op))
 (def-infix := :==)
 (def-infix :not= "~=")
-(def-infix :set :=)
+
+(fn forms.set [[left right] scope]
+    (.. (comp.expr left scope) " = (" (comp.expr right scope) ")"))
 
 (fn comp.quote [stmts scope]
     (if (= (length stmts) 1) (.. "`(" (comp.expr (. stmts 1) scope) ")")
-        (.. "quote\n" (commasep stmts #(comp.expr $1 scope) "\n") "\nend")))
+        (.. "quote\n" (commasep stmts #(comp.expr $1 scope)) "\nend")))
+
+(fn comp.global [[typ initial-val] scope]
+    (.. "global(" (comp.type typ scope) "," (comp.expr initial-val scope) ")"))
 
 (fn build [expr compiler]
     (let [scope (new-scope)
@@ -209,7 +223,9 @@
 
 (fn def [...] (terra `(,(sym :def) ,...)))
 (fn q [...] (build [...] comp.quote))
+(fn static [typ initial-value] (build [typ initial-value] comp.global))
+
 (fn unterra [...] (view (macroexpand (terra ...))))
 (fn untype [...] (view (macroexpand (ttype ...))))
 
-{: terra : ttype : def : q : unterra : untype}
+{: terra : ttype : def : q : static : unterra : untype}