From e046b4462eee302d541d42566712637d239466ae Mon Sep 17 00:00:00 2001
From: Nat Quayle Nelson <natquaylenelson@gmail.com>
Date: Tue, 28 Jun 2022 04:40:13 +0000
Subject: [PATCH] generic function parameters

---
 src/kiss/FieldForms.hx   | 10 +++++++++-
 src/kiss/Helpers.hx      | 24 +++++++++++++++++++++---
 src/kiss/Kiss.hx         |  3 ++-
 src/kiss/Reader.hx       | 12 ++++++++++++
 src/kiss/ReaderExp.hx    |  1 +
 src/kiss/SpecialForms.hx |  2 +-
 6 files changed, 46 insertions(+), 6 deletions(-)

diff --git a/src/kiss/FieldForms.hx b/src/kiss/FieldForms.hx
index bdbeb9d..6d8f382 100644
--- a/src/kiss/FieldForms.hx
+++ b/src/kiss/FieldForms.hx
@@ -124,6 +124,13 @@ class FieldForms {
             var returnsValue = !isVoid(args[0]);
 
             var wasInStatic = k.inStaticFunction;
+            var typeParams = switch (args[1].def) {
+                case TypeParams(p):
+                    args.splice(1, 1);    
+                    p;
+                default:
+                    [];
+            } 
 
             var f:Field = {
                 name: name,
@@ -135,7 +142,8 @@ class FieldForms {
                         args[1],
                         args.slice(2),
                         k.forStaticFunction(inStaticFunction),
-                        formName)),
+                        formName,
+                        typeParams)),
                 pos: wholeExp.macroPos()
             };
 
diff --git a/src/kiss/Helpers.hx b/src/kiss/Helpers.hx
index e9b195a..afb415f 100644
--- a/src/kiss/Helpers.hx
+++ b/src/kiss/Helpers.hx
@@ -109,14 +109,31 @@ class Helpers {
         };
     }
 
-    // TODO generic type parameter declarations
-    public static function makeFunction(?name:ReaderExp, returnsValue:Bool, argList:ReaderExp, body:List<ReaderExp>, k:KissState, formName:String):Function {
+    public static function makeTypeParam(param:ReaderExp, ?constraints:Array<ComplexType> = null):TypeParamDecl {
+        if (constraints == null) constraints = [];
+        switch (param.def) {
+            case Symbol(name):
+                return {
+                    name: name,
+                    constraints: constraints
+                };
+            case TypedExp(type, param):
+                constraints.push(parseComplexType(type));
+                return makeTypeParam(param, constraints);
+            default:
+                throw KissError.fromExp(param, "expected <GenericTypeName> or :<Constraint> <GenericTypeName>");
+        }
+    }
+
+    public static function makeFunction(?name:ReaderExp, returnsValue:Bool, argList:ReaderExp, body:List<ReaderExp>, k:KissState, formName:String, typeParams:Array<ReaderExp>):Function {
         var funcName = if (name != null) {
             varName(formName, name, "function");
         } else {
             "";
         };
 
+        var params = [for (p in typeParams) makeTypeParam(p)];
+
         var numArgs = 0;
         // Once the &opt meta appears, all following arguments are optional until &rest
         var opt = false;
@@ -218,7 +235,8 @@ class Helpers {
         return {
             ret: if (name != null) Helpers.explicitType(name) else null,
             args: args,
-            expr: expr
+            expr: expr,
+            params: params
         };
     }
 
diff --git a/src/kiss/Kiss.hx b/src/kiss/Kiss.hx
index 1325960..7895f59 100644
--- a/src/kiss/Kiss.hx
+++ b/src/kiss/Kiss.hx
@@ -307,7 +307,8 @@ class Kiss {
                             b.list([]),
                             [topLevelBegin],
                             k,
-                            "function")),
+                            "function",
+                            [])),
                         pos: topLevelBegin.macroPos()
                     });
                 }
diff --git a/src/kiss/Reader.hx b/src/kiss/Reader.hx
index d88c766..ba9e5bb 100644
--- a/src/kiss/Reader.hx
+++ b/src/kiss/Reader.hx
@@ -39,6 +39,8 @@ class Reader {
         // and also handles string interpolation cases like "${exp}moreString"
         readTable["{"] = (stream:Stream, k) -> CallExp(Symbol("begin").withPos(stream.position()), readExpArray(stream, "}", k));
 
+        readTable["<>["] = (stream, k) -> TypeParams(readExpArray(stream, "]", k));
+
         readTable['"'] = readString.bind(_, _, false);
         readTable["#"] = readRawString;
 
@@ -506,6 +508,16 @@ class Reader {
                 ].join(" ");
                 str += ']';
                 str;
+            case TypeParams(exps):
+                // <>[T1 T2 T3]
+                var str = '<>[';
+                str += [
+                    for (exp in exps) {
+                        exp.def.toString();
+                    }
+                ].join(" ");
+                str += ']';
+                str;
             case StrExp(s):
                 // "literal"
                 '"$s"';
diff --git a/src/kiss/ReaderExp.hx b/src/kiss/ReaderExp.hx
index 6c32688..26c50db 100644
--- a/src/kiss/ReaderExp.hx
+++ b/src/kiss/ReaderExp.hx
@@ -23,5 +23,6 @@ enum ReaderExpDef {
     UnquoteList(exp:ReaderExp); // ,@[exp]
     ListEatingExp(exps:Array<ReaderExp>); // [::exp exp ...exps exp]
     ListRestExp(name:String); // ...exps or ...
+    TypeParams(types:Array<ReaderExp>); // <>[T :Constraint U :Constraint1 :Constraint2 V]
     None; // not an expression, i.e. (#unless falseCondition exp)
 }
diff --git a/src/kiss/SpecialForms.hx b/src/kiss/SpecialForms.hx
index 65e20c2..9e00e06 100644
--- a/src/kiss/SpecialForms.hx
+++ b/src/kiss/SpecialForms.hx
@@ -230,7 +230,7 @@ class SpecialForms {
                 default:
                     true;
             }
-            EFunction(FAnonymous, Helpers.makeFunction(null, returnsValue, args[0], args.slice(1), k, "lambda")).withMacroPosOf(wholeExp);
+            EFunction(FAnonymous, Helpers.makeFunction(null, returnsValue, args[0], args.slice(1), k, "lambda", [])).withMacroPosOf(wholeExp);
         };
     
         function forExpr(formName:String, wholeExp:ReaderExp, args:Array<ReaderExp>, k:KissState) {