Not sure what I just fixed.

Not needed with new GC.

README.md

@@ -1,20 +1,20 @@
 # SCL: Simple CAS Language
 
-Version v0.3
+*v0.3*
 
 SCL aims to be a human-friendly Computer Algebra System (CAS) inspired by
 [maxima](https://maxima.sourceforge.io/) that feels like writing on paper. In
 its current state, SCL can be used as a functional programming language capable
-of performing simple arithmetic. The codebase is about 2,000 lines of C,
-including a parser, interpreter, and runtime. It uses a linked environment
-scoping model.
+of performing simple arithmetic. The codebase is about 2,000 lines of
+handwritten C, including a parser, interpreter, and runtime. It uses a linked
+environment scoping model.
 
 ## Usage
 
 To download and run:
 
 ```bash
-git clone https://git.signorovitch.org/jacob/scl -b stable && cd scl
+git clone https://git.signorovitch.org/scl/scl -b stable && cd scl
 make release
 ./scl.out
 ```
@@ -22,35 +22,25 @@ make release
 ### For Development
 
 ```bash
-git clone git@signorovitch.org:jacob/scl --recurse-submodules && cd scl
+git clone git@signorovitch.org:scl/scl --recurse-submodules && cd scl
 make all test
 ./scl.out
 ```
 
 If you wish to run tests, make sure to run `git clone --recurse-submodules` to
 include the [Unity](https://github.com/ThrowTheSwitch/Unity) test framework.
+*Note that tests are currently in poor use. I hope to amend this in the future.*
 
 ## Syntax
 
-As one would expect, you can evaluate simple infix expressions:
+SCL's syntax will feel familiar to other functional programming languages.
 
 ```scl
-> 1 + 1
+> x = 3 + 3 * 3; x + 1
+= 13
+> f(x) x + 1
+> f(1)
 = 2
-```
-
-You can also define your own functions and variables:
-
-```scl
-> f(x) 2 * x
-> n = 3
-> f(n)
-= 6
-```
-
-Being a functional programming language at heart, one can of course use lambda functions:
-
-```scl
 > (\(x) 2 * x)(5)
 = 10
 > f(g) g(2)
@@ -58,17 +48,24 @@ Being a functional programming language at heart, one can of course use lambda f
 = 4
 ```
 
-Here's a simple factorial function:
+Here's a simple factorial function, using recursion:
 
 ```scl
-> factorial(n) {
->   if (n == 0) { 1 }
->   else { n * factorial(n - 1) }
+> fac(n) = {
+>   f(n, a) = {
+>     if n == 1
+>       a
+>     else
+>       f(n - 1, a * n);
+>   }
+>
+>   f(n, 1);
 > }
 ```
 
-Or, using SCL's more concise syntax:
+SCL's syntax is quite flexible. The above function could be more concisely
+written as:
 
 ```scl
-> factorial(n) ? n == 0 1 n * factorial(n - 1)
+> fac(n) (n, 1) -> f(n, a) ? n == 1 a f(n - 1, a * n)
 ```

TODO.md

@@ -1,3 +1,4 @@
+Differentiate kind literals, constructors, and kinds themselves.
 EXCEPTION HANDLING: exception ast type should have as data a giant enum of
 possible types, rather than a char* message. A description of each type could be
 handled under the exception type and print logic. For now, executor checks

examples/types.scl

@@ -1,48 +1,3 @@
-# Vectors
-# - Must have fixed size and type
+x: Int = 3
 
-# Lists
-# - Variable size, variable type
-
-# Define a variable of type int:
-n: int = 3
-
-# Define v as a 3-dimensional vector of integers:
-v: int<3> = <4, 5, 6>
-
-# Define l as list of length 3:
-l: [3] = [1, 2, "These can be any type at all"]
-# This would also work, as length values for lists are optional (and mutable),
-# unlike vectors:
-l: [] = [1, 2, "whatever"]
-# This is also the same, being more explicit about the any type:
-l: any[] = [1, 2, "whatever"]
-# This must be a list of integers, however:
-l: int[] = [1, 2, 3]
-
-# Define a list of either integers or strings:
-l: union(int, str)[] = ["hello", 4, "world"]
-# union() is a complex type generator; "returns" a union of the int and str types.
-
-# Use vectors wherever possible, as they are much faster than lists.
-
-# Matrix
-# - Must have a fixed size and type (just like vectors)
-m: int<2, 2> = <<0, 1>, <2, 3>>
-# Can also be written as
-m: int<2, 2> = <<0, 1, 2, 3>>
-# When using this syntax, will fill remaining space with default value of type
-# to make data rectangular. E.g., to fill a 2 x 2 matrix with 0:
-m: int<2, 2> = <<>>
-
-# To define custom data types, e.g. structs:
-typedef(Vec2, struct( a: int, b: int ))
-vector_two: Vec2 = Vec2(2, 3)
-
-typedef(IntOrStr, union(str, int))
-one: IntOrStr = 1
-alsoOne: IntOrStr = "one"
-
-# To define custom data types with type arguments:
-typedef(Vec1Of(T), T<1>)
-hello: Vec1Of(str) = <"Hello">
+<name> : <expression> = <expression>

src/ast.c

@@ -41,14 +41,17 @@ void ast_destroy(AST* ast) {
     switch (ast->type) {
         case AST_TYPE_LIT_NUM:  ast_num_data_destroy(ast->data); break;
         case AST_TYPE_LIT_BOOL: ast_bool_data_destroy(ast->data); break;
+        case AST_TYPE_LIT_KIND: ast_kind_data_destroy(ast->data); break;
         case AST_TYPE_CALL:     ast_call_data_destroy(ast->data); break;
-        case AST_TYPE_VREF:     ast_vref_data_destroy(ast->data); break;
-        case AST_TYPE_VDEF:     ast_vdef_data_destroy(ast->data); break;
-        case AST_TYPE_BLOCK:    ast_block_data_destroy_psv(ast->data); break;
+        case AST_TYPE_REF:      ast_ref_data_destroy(ast->data); break;
+        case AST_TYPE_DEF:      ast_def_data_destroy(ast->data); break;
+        case AST_TYPE_BLOCK:    ast_block_data_destroy(ast->data); break;
         case AST_TYPE_ARG:      ast_arg_data_destroy(ast->data); break;
         case AST_TYPE_BIF:      ast_bif_data_destroy(ast->data); break;
         case AST_TYPE_EXC:      ast_exc_data_destroy(ast->data); break;
         case AST_TYPE_LAMBDA:   ast_lambda_data_destroy(ast->data); break;
+        case AST_TYPE_FORCE:    ast_force_data_destroy(ast->data); break;
+        case AST_TYPE_PRESERVE: ast_preserve_data_destroy(ast->data); break;
         default:
             log_dbgf("Unknown ast type %d (max: %d)", ast->type, AST_TYPE_MAX);
     }
@@ -76,6 +79,21 @@ ASTBoolData* ast_bool_data_init(int val) {
 
 void ast_bool_data_destroy(ASTBoolData* bol) { free(bol); }
 
+const char* ast_lit_kind_names[AST_LIT_KIND_MAX + 2] = {
+    [AST_LIT_KIND_NUM] = "Number",
+    [AST_LIT_KIND_BOOL] = "Boolean",
+    [AST_LIT_KIND_KIND] = "Type",
+};
+
+ASTKindData* ast_kind_data_init(ASTKindData val) {
+    talloc(ASTKindData, kind);
+    *kind = val;
+
+    return kind;
+}
+
+void ast_kind_data_destroy(ASTKindData* kind) { free(kind); }
+
 ASTExcData* ast_exc_data_init(const char* msg, AST* trace) {
     ASTExcData* data = malloc(sizeof(ASTExcData));
     data->msg = msg;
@@ -129,35 +147,36 @@ void ast_call_data_destroy(ASTCallData* call) {
     free(call);
 }
 
-// VDef.
+// Def.
 
-ASTVDefData* ast_vdef_data_init(char* name, AST* exp) {
-    talloc(ASTVDefData, vdef);
+ASTDefData* ast_def_data_init(char* name, AST* kind, AST* exp) {
+    talloc(ASTDefData, def);
 
-    vdef->name = name;
-    vdef->exp = exp;
+    def->name = name;
+    def->kind = kind;
+    def->exp = exp;
 
-    return vdef;
+    return def;
 }
 
-void ast_vdef_data_destroy(ASTVDefData* vdef) {
+void ast_def_data_destroy(ASTDefData* vdef) {
     free(vdef->name);
     free(vdef);
 }
 
-// VRef.
+// Ref.
 
-ASTVrefData* ast_vref_data_init(char* to) {
-    talloc(ASTVrefData, vref);
+ASTRefData* ast_ref_data_init(char* to) {
+    talloc(ASTRefData, ref);
 
-    vref->to = to;
+    ref->to = to;
 
-    return vref;
+    return ref;
 }
 
-void ast_vref_data_destroy(ASTVrefData* vref) {
-    free(vref->to);
-    free(vref);
+void ast_ref_data_destroy(ASTRefData* ref) {
+    free(ref->to);
+    free(ref);
 }
 
 ASTBlockData* ast_block_data_init(AST** inside, size_t ln) {
@@ -170,13 +189,6 @@ ASTBlockData* ast_block_data_init(AST** inside, size_t ln) {
 }
 
 void ast_block_data_destroy(ASTBlockData* block) {
-    for (size_t i = 0; i < block->ln; i++) { ast_destroy(block->inside[i]); }
-
-    free(block->inside);
-    free(block);
-}
-
-void ast_block_data_destroy_psv(ASTBlockData* block) {
     free(block->inside);
     free(block);
 }
@@ -198,3 +210,19 @@ AST* ast_find(Scope* scope, char* name) {
 
     return NULL;
 }
+
+ASTForceData* ast_force_data_init(AST* body) {
+    talloc(ASTForceData, force);
+    force->body = body;
+    return force;
+}
+
+void ast_force_data_destroy(ASTForceData* force) { free(force); }
+
+ASTPreserveData* ast_preserve_data_init(AST* body) {
+    talloc(ASTPreserveData, preserve);
+    preserve->body = body;
+    return preserve;
+}
+
+void ast_preserve_data_destroy(ASTPreserveData* preserve) { free(preserve); }

src/ast_print.c

@@ -6,17 +6,18 @@
 #include <stdio.h>
 
 static char* asttype_names[] = {
-    [AST_TYPE_CALL] = "FUNC CALL",
-    [AST_TYPE_LIT_NUM] = "NUMBER",
-    [AST_TYPE_LIT_BOOL] = "BOOLEAN",
-    [AST_TYPE_LIT_KIND] = "KIND",
-    [AST_TYPE_VREF] = "VAR REFERENCE",
-    [AST_TYPE_VDEF] = "VAR DEFINITION",
+    [AST_TYPE_CALL] = "CALL",
+    [AST_TYPE_LIT_NUM] = "LITERAL NUMBER",
+    [AST_TYPE_LIT_BOOL] = "LITERAL BOOLEAN",
+    [AST_TYPE_REF] = "REFERENCE",
+    [AST_TYPE_DEF] = "DEFINITION",
     [AST_TYPE_BLOCK] = "BLOCK",
     [AST_TYPE_EXC] = "EXCEPTION",
     [AST_TYPE_ARG] = "DEFINITION ARGUMENT",
-    [AST_TYPE_LAMBDA] = "LAMBDA EXPRESSION",
-    [AST_TYPE_BIF] = "BUILTIN FUNCTION"
+    [AST_TYPE_LAMBDA] = "LAMBDA",
+    [AST_TYPE_BIF] = "BUILTIN FUNCTION",
+    [AST_TYPE_FORCE] = "FORCE",
+    [AST_TYPE_PRESERVE] = "PRESERVE"
 };
 
 void ast_print(AST* ast) {
@@ -40,15 +41,23 @@ void ast_print_i(AST* ast, int i) {
                 *(ASTBoolData*)ast->data ? "true" : "false"
             );
             break;
-        case AST_TYPE_CALL:   ast_call_print(ast->data, i + 2); break;
-        case AST_TYPE_EXC:    ast_exc_print(ast->data, i + 2); break;
-        case AST_TYPE_VREF:   ast_vref_print(ast->data, i + 2); break;
-        case AST_TYPE_VDEF:   ast_vdef_print(ast->data, i + 2); break;
-        case AST_TYPE_BLOCK:  ast_block_print(ast->data, i + 2); break;
-        case AST_TYPE_ARG:    ast_arg_print(ast->data, i + 2); break;
-        case AST_TYPE_LAMBDA: ast_lambda_print(ast->data, i + 2); break;
-        case AST_TYPE_BIF:    ast_bif_print(ast->data, i + 2); break;
-        default:              exit(1);
+        case AST_TYPE_LIT_KIND:
+            printf(
+                "%s  %s\n", INDENT_spacing->buf,
+                ast_lit_kind_names[*(ASTKindData*)ast->data]
+            );
+            break;
+        case AST_TYPE_CALL:     ast_call_print(ast->data, i + 2); break;
+        case AST_TYPE_EXC:      ast_exc_print(ast->data, i + 2); break;
+        case AST_TYPE_REF:      ast_ref_print(ast->data, i + 2); break;
+        case AST_TYPE_DEF:      ast_def_print(ast->data, i + 2); break;
+        case AST_TYPE_BLOCK:    ast_block_print(ast->data, i + 2); break;
+        case AST_TYPE_ARG:      ast_arg_print(ast->data, i + 2); break;
+        case AST_TYPE_LAMBDA:   ast_lambda_print(ast->data, i + 2); break;
+        case AST_TYPE_BIF:      ast_bif_print(ast->data, i + 2); break;
+        case AST_TYPE_FORCE:    ast_force_print(ast->data, i + 2); break;
+        case AST_TYPE_PRESERVE: ast_preserve_print(ast->data, i + 2); break;
+        default:                exit(1);
     }
     INDENT_FIELD_NONL_END;
     INDENT_END;
@@ -97,22 +106,28 @@ void ast_call_print(ASTCallData* data, int i) {
 
     INDENT_END;
 }
-void ast_vdef_print(ASTVDefData* vdef, int depth) {
+void ast_def_print(ASTDefData* def, int depth) {
     INDENT_BEGIN(depth);
 
-    INDENT_TITLE("ASTVDefData", vdef);
-    INDENT_FIELD("name", "%s", vdef->name);
+    INDENT_TITLE("ASTDefData", def);
+    INDENT_FIELD("name", "%s", def->name);
+    if (def->kind) {
+        INDENT_FIELD_EXT_NONL_START("kind");
+        ast_print_i(def->kind, depth + 2);
+        INDENT_FIELD_NONL_END;
+    } else INDENT_FIELD("kind", "%s", "Any");
+
     INDENT_FIELD_EXT_NONL_START("exp");
-    ast_print_i(vdef->exp, depth + 2); // 2 because already indented.
+    ast_print_i(def->exp, depth + 2); // 2 because already indented.
     INDENT_FIELD_NONL_END;
 
     INDENT_END;
 }
 
-void ast_vref_print(ASTVrefData* data, int i) {
+void ast_ref_print(ASTRefData* data, int i) {
     INDENT_BEGIN(i);
 
-    INDENT_TITLE("ASTVrefData", data);
+    INDENT_TITLE("ASTRefData", data);
     INDENT_FIELD("to", "%s", data->to);
 
     INDENT_END;
@@ -160,3 +175,25 @@ void ast_bif_print(ASTBIFData* bif, int i) {
     INDENT_FIELD("name", "%s", name);
     INDENT_END;
 }
+
+void ast_force_print(ASTForceData* force, int i) {
+    INDENT_BEGIN(i);
+
+    INDENT_TITLE("ASTForceData", force);
+    INDENT_FIELD_EXT_NONL_START("body");
+    ast_print_i(force->body, i + 2);
+    INDENT_FIELD_NONL_END;
+
+    INDENT_END;
+}
+
+void ast_preserve_print(ASTPreserveData* preserve, int i) {
+    INDENT_BEGIN(i);
+
+    INDENT_TITLE("ASTPreserveData", preserve);
+    INDENT_FIELD_EXT_NONL_START("body");
+    ast_print_i(preserve->body, i + 2);
+    INDENT_FIELD_NONL_END;
+
+    INDENT_END;
+}

src/exec.c

@@ -23,6 +23,18 @@ AST* exec_start(AST* ast) {
             ast_init(AST_TYPE_BIF, ast_bif_data_init(BUILTIN_FNS[i].fn))
         );
 
+    AST* defnum =
+        ast_init(AST_TYPE_LIT_KIND, ast_kind_data_init(AST_LIT_KIND_NUM));
+    htab_ins(global->here, "Num", defnum);
+
+    AST* defbool =
+        ast_init(AST_TYPE_LIT_KIND, ast_kind_data_init(AST_LIT_KIND_BOOL));
+    htab_ins(global->here, "Bool", defbool);
+
+    AST* defkind =
+        ast_init(AST_TYPE_LIT_KIND, ast_kind_data_init(AST_LIT_KIND_KIND));
+    htab_ins(global->here, "Type", defkind);
+
     log_dbg("Completed startup sequence.");
 
     AST* res = exec_exp(ast, global);
@@ -42,11 +54,13 @@ AST* exec_exp(AST* ast, Scope* parent) {
             return ast_init(
                 AST_TYPE_LIT_BOOL, ast_bool_data_init(*(ASTBoolData*)ast->data)
             );
-        case AST_TYPE_VREF:   return exec_vref(ast, parent);
-        case AST_TYPE_VDEF:   return exec_vdef(ast, parent);
+        case AST_TYPE_REF:      return exec_ref(ast, parent);
+        case AST_TYPE_DEF:      return exec_def(ast, parent);
         case AST_TYPE_BIF:
-        case AST_TYPE_LAMBDA: return ast;
-        default:              printf("what\n"); exit(1);
+        case AST_TYPE_LAMBDA:   return ast;
+        case AST_TYPE_FORCE:    return exec_force(ast, parent);
+        case AST_TYPE_PRESERVE: return exec_preserve(ast, parent);
+        default:                printf("what\n"); exit(1);
     }
 }
 
@@ -70,8 +84,9 @@ AST* exec_call(AST* ast, Scope* parent) {
 
     switch (exp->type) {
         case AST_TYPE_BIF:
-            ASTBIFData bifdata = exp->data;
-            return bifdata(calldata->argc, calldata->argv, parent);
+            return ((ASTBIFData)exp->data)(
+                calldata->argc, calldata->argv, parent
+            );
         case AST_TYPE_LAMBDA:
             return exec_lambda(calldata->argc, calldata->argv, exp, parent);
         default:
@@ -81,31 +96,52 @@ AST* exec_call(AST* ast, Scope* parent) {
     }
 }
 
-AST* exec_vdef(AST* ast, Scope* parent) {
+AST* exec_def(AST* ast, Scope* parent) {
     // Use parent's scope.
     exec_inherit_scope(ast, parent);
 
-    ASTVDefData* data = (ASTVDefData*)ast->data;
+    ASTDefData* data = (ASTDefData*)ast->data;
     AST* val = data->exp;
     char* key = data->name;
+
+    if (data->kind) {
+
+        ASTKindData kind = *(ASTKindData*)exec_exp(data->kind, parent)->data ==
+                           AST_LIT_KIND_NUM;
+
+        if (kind == AST_LIT_KIND_NUM && data->exp->type != AST_TYPE_LIT_NUM)
+            return ast_init(
+                AST_TYPE_EXC, ast_exc_data_init("Expected Num.", NULL)
+            );
+
+        if (kind == AST_LIT_KIND_BOOL && data->exp->type != AST_TYPE_LIT_BOOL)
+            return ast_init(
+                AST_TYPE_EXC, ast_exc_data_init("Expected Bool.", NULL)
+            );
+
+        if (kind == AST_LIT_KIND_KIND && data->exp->type != AST_TYPE_LIT_KIND)
+            return ast_init(
+                AST_TYPE_EXC, ast_exc_data_init("Expected Type.", NULL)
+            );
+    }
+
     scope_add(parent, key, val); // Add variable definition to parent scope.
     return exec_exp(val, parent);
 }
 
-AST* exec_vref(AST* ast, Scope* parent) {
+AST* exec_ref(AST* ast, Scope* parent) {
     // Use parent's scope.
     exec_inherit_scope(ast, parent);
     log_dbg("attempting to reference var");
-    ASTVrefData* vref = (ASTVrefData*)ast->data;
+    ASTRefData* ref = (ASTRefData*)ast->data;
 
-    AST* found = ast_find(parent, vref->to);
+    AST* found = ast_find(parent, ref->to);
 
     if (found == NULL) {
         // TODO: Better memory management here.
         static char msg[256];
         snprintf(
-            msg, sizeof(msg), "Could not find value in scope for `%s`.",
-            vref->to
+            msg, sizeof(msg), "Could not find value in scope for `%s`.", ref->to
         );
         return ast_init(AST_TYPE_EXC, ast_exc_data_init(msg, NULL));
     }
@@ -114,15 +150,6 @@ AST* exec_vref(AST* ast, Scope* parent) {
     return found;
 }
 
-AST* exec_fdef(AST* ast, Scope* parent) {
-    ast->scope = scope_init(parent);
-    ASTFDefData* fdef = (ASTFDefData*)ast->data;
-    AST* val = ast;
-    char* key = fdef->name;
-    scope_add(parent, key, val);
-    return fdef->body; // Function definitions return function body.
-}
-
 AST* exec_lambda(size_t argc, AST** argv, AST* exp, Scope* parent) {
     Scope* callscope = scope_init(parent);
     ASTLambdaData* lambda = (ASTLambdaData*)exp->data;
@@ -135,6 +162,18 @@ AST* exec_lambda(size_t argc, AST** argv, AST* exp, Scope* parent) {
     return exec_exp(lambda->body, callscope);
 }
 
+AST* exec_force(AST* ast, Scope* parent) {
+    AST* body = ((ASTForceData*)ast->data)->body;
+
+    if (body->type == AST_TYPE_REF) {
+        return exec_exp(exec_ref(body, parent), parent);
+    } else return exec_exp(body, parent);
+}
+
+AST* exec_preserve(AST* ast, Scope* parent) {
+    return ((ASTPreserveData*)ast->data)->body;
+}
+
 void exec_print(double n) { printf("= %lf\n", n); }
 
 inline void exec_new_scope(AST* ast, Scope* inherit) {

src/fnv1a.c

@@ -1,6 +1,9 @@
 #include "include/fnv1a.h"
+#include "include/util.h"
+#include "include/util.h"
 
 #include <stdlib.h>
+#include <stdio.h>
 
 uint64_t fnv1a_hash(char* key, size_t ln) {
     uint64_t hash = FNV1A_BASIS_64;
@@ -10,5 +13,7 @@ uint64_t fnv1a_hash(char* key, size_t ln) {
         hash *= FNV1A_PRIME_64;
     }
 
+    log_dbgf("Hash of %s was %lu", key, hash);
+
     return hash;
 }

src/gc.c

@@ -11,8 +11,6 @@ GC* gclist = NULL;
 
 void gc_destroy(GC* gc) { free(gc); }
 
-void f() {}
-
 void* gc_alloc(size_t sz, GCType type) {
     assert(type <= GC_TYPE_MAX);
 
@@ -40,7 +38,6 @@ void gc_hack_free() {
         gclist = gclist->nxt;
         switch (gc->type) {
             case GC_TYPE_AST:
-                f();
                 if (((AST*)gc->p)->type > AST_TYPE_MAX) {
                     log_dbgf(
                         "Attempted to free invalid AST (%i > %i) to GC: gc:%p "

src/grammar.y

@@ -44,6 +44,9 @@
 %token EQ // Equals =.
 %token DEQ // Double equals ==.
 
+%token RARROW // Right arrow ->.
+%token LARROW // Left arrow <-.
+
 %token EXPSEP // Expression seperator ;.
 
 %token<strval> WORD // Word, i.e. keyword.
@@ -56,10 +59,19 @@
 
 %token NL // Newline.
 
+%token COLON // Colon :.
+%token STOP // Stop sign $.
+
+%token FORCE // Force operator !.
+%token PRESERVE // Preserve operator @.
+
 %token BACKSLASH
 
 %left ADD SUB
 %left MUL DIV
+%left RARROW
+%right LARROW
+%nonassoc STOP
 %precedence NEG
 
 %type<ast> exp;
@@ -74,6 +86,8 @@
 
 %%
 
+maybe_stop: %empty | STOP;
+
 inputstart:
     exp {
         DList* exps = dlist_init();
@@ -132,9 +146,99 @@ block:
     }
     ;
 
+
 exp:
+    // Stop sign.
+    exp STOP { $$ = $1; }
+
+    // Variable reference.
+    | WORD {
+        $$ = ast_init(AST_TYPE_REF, ast_ref_data_init($1));
+    }
+
+    // Call (general form).
+    | exp GROUPS arg GROUPE {
+        size_t argc = $3->ln;
+        AST** argv = $3->buf;
+        argarr_destroypsv($3);
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
+            argc,
+            argv,
+            $1
+        ));
+    }
+
+    // Call (general hacky form).
+    | exp GROUPS GROUPE {
+        size_t argc = 1;
+        AST** argv = NULL;
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
+            argc,
+            argv,
+            $1
+        ));
+    }
+
+    // Call (right arrow general form).
+    | GROUPS arg GROUPE RARROW exp {
+        size_t argc = $2->ln;
+        AST** argv = $2->buf;
+        argarr_destroypsv($2);
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
+            argc,
+            argv,
+            $5
+        ));
+    }
+
+    | exp RARROW exp {
+        size_t argc = 1;
+        AST** argv = malloc(sizeof(AST*));
+        argv[0] = $1;
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
+            argc,
+            argv,
+            $3
+        ));
+    }
+
+    | exp LARROW exp {
+        size_t argc = 1;
+        AST** argv = malloc(sizeof(AST*));
+        argv[0] = $3;
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
+            argc,
+            argv,
+            $1
+        ));
+    }
+
+    // Call (convenient form).
+    | WORD GROUPS arg GROUPE {
+        size_t argc = $3->ln;
+        AST** argv = $3->buf;
+        argarr_destroypsv($3);
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
+            argc,
+            argv,
+            ast_init(AST_TYPE_REF, ast_ref_data_init($1))
+        ));
+    }
+
+
+    // Call (hacky convenient form).
+    | WORD GROUPS GROUPE {
+        size_t argc = 0;
+        AST** argv = NULL;
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
+            argc,
+            argv,
+            ast_init(AST_TYPE_REF, ast_ref_data_init($1))
+        ));
+    }
+
     // Number.
-    NUM { $$ = ast_init(AST_TYPE_LIT_NUM, ast_num_data_init($1)); }
+    | NUM { $$ = ast_init(AST_TYPE_LIT_NUM, ast_num_data_init($1)); }
 
     | BOOLT { $$ = ast_init(AST_TYPE_LIT_BOOL, ast_bool_data_init(1)); }
     | BOOLF { $$ = ast_init(AST_TYPE_LIT_BOOL, ast_bool_data_init(0)); }
@@ -163,6 +267,7 @@ exp:
             ast_init(AST_TYPE_BIF, ast_bif_data_init(builtin_if))
         ));
     }
+
     | IF exp exp ELSE exp {
         AST** argv = calloc(3, sizeof(AST*));
         argv[0] = $2;
@@ -176,53 +281,14 @@ exp:
         ));
     }
 
-    // Variable reference.
-    | WORD {
-        $$ = ast_init(AST_TYPE_VREF, ast_vref_data_init($1));
-    }
-
-    // Call (general form).
-    | exp GROUPS arg GROUPE {
-        size_t argc = $3->ln;
-        AST** argv = $3->buf;
-        argarr_destroypsv($3);
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
-            argc,
-            argv,
-            $1
-        ));
-    }
-
-    // Call (convenient form).
-    | WORD GROUPS arg GROUPE {
-        size_t argc = $3->ln;
-        AST** argv = $3->buf;
-        argarr_destroypsv($3);
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
-            argc,
-            argv,
-            ast_init(AST_TYPE_VREF, ast_vref_data_init($1))
-        ));
-    }
-
-    // Call (hacky convenient form).
-    | WORD GROUPS GROUPE {
-        size_t argc = 0;
-        AST** argv = NULL;
-        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
-            argc,
-            argv,
-            ast_init(AST_TYPE_VREF, ast_vref_data_init($1))
-        ));
-    }
-
-    // Function definitions. Convert to VDef of Lambda.
-    | WORD GROUPS arg GROUPE exp {
+    // Function definitions. Convert to Def of Lambda.
+    | WORD GROUPS arg GROUPE exp maybe_stop {
         size_t parc = $3->ln;
         AST** parv = $3->buf;
         argarr_destroypsv($3);
-        $$ = ast_init(AST_TYPE_VDEF, ast_vdef_data_init(
+        $$ = ast_init(AST_TYPE_DEF, ast_def_data_init(
             $1,
+            NULL,
             ast_init(AST_TYPE_LAMBDA, ast_lambda_data_init(
                 parc, parv, $5
             ))
@@ -237,9 +303,21 @@ exp:
         $$ = ast_init(AST_TYPE_LAMBDA, ast_lambda_data_init(parc, parv, $5));
     }
 
+    // Force operator.
+    | FORCE exp {
+        $$ = ast_init(AST_TYPE_FORCE, ast_force_data_init($2));
+    }
+
+    // Preserve operator.
+    | PRESERVE exp {
+        $$ = ast_init(AST_TYPE_PRESERVE, ast_preserve_data_init($2));
+    }
+
     // Block.
     | BLOCKS block BLOCKE {
-        $$ = ast_init(AST_TYPE_BLOCK, ast_block_data_init((AST**) $2->buf, $2->ln));
+        AST** exps = (AST**) $2->buf;
+        dlist_destroypsv($2);
+        $$ = ast_init(AST_TYPE_BLOCK, ast_block_data_init((AST**) exps, $2->ln));
     }
 
     // Negative.
@@ -261,9 +339,23 @@ exp:
     // Group.
     | GROUPS exp GROUPE { $$ = $2; }
 
-    // Variable definition.
+    // Definition with type annotation.
+    | WORD COLON exp EQ exp {
+        $$ = ast_init(AST_TYPE_DEF, ast_def_data_init($1, $3, $5));
+    }
+
+    // Definition with type annotation.
+    | WORD COLON WORD EQ exp {
+        $$ = ast_init(AST_TYPE_DEF, ast_def_data_init(
+            $1,
+            ast_init(AST_TYPE_REF, ast_ref_data_init($3)),
+            $5
+        ));
+    }
+
+    // Definition.
     | WORD EQ exp {
-        $$ = ast_init(AST_TYPE_VDEF, ast_vdef_data_init($1, $3));
+        $$ = ast_init(AST_TYPE_DEF, ast_def_data_init($1, NULL, $3));
     }
 
     | exp ADD exp {

src/include/ast.h

@@ -9,25 +9,30 @@ typedef enum {
     // Primitive type literals.
     AST_TYPE_LIT_NUM,  // A number (float) literal.
     AST_TYPE_LIT_BOOL, // A boolean literal.
+    AST_TYPE_LIT_VEC,  // A vector literal.
     AST_TYPE_LIT_KIND, // A kind literal.
 
-    AST_TYPE_INT,  // An integer.
-    AST_TYPE_SYM,  // A symbol.
-    AST_TYPE_EXC,  // Exception.
+    AST_TYPE_EXC_CON,  // Exception constructor `Exc`.
+    AST_TYPE_VEC_CON,  // Vectpr constructor `Vec()`.
 
     // Collection types:
     AST_TYPE_VEC,  // A vector (fixed size, fixed type).
     AST_TYPE_LIST, // A list (variable size, variable type).
 
+    // Syntactic types:
+    AST_TYPE_FORCE,
+    AST_TYPE_PRESERVE,
+    AST_TYPE_BLOCK,  // A block of code (scope).
+    AST_TYPE_ARG,    // A definition argument.
+
     // Misc. types.
     AST_TYPE_BIF,    // Built-in function.
     AST_TYPE_CALL,   // A function call.
-    AST_TYPE_VDEF,   // A variable definition.
-    AST_TYPE_VREF,   // A variable reference.
-    AST_TYPE_BLOCK,  // A block of code (scope).
+    AST_TYPE_DEF,   // A definition.
+    AST_TYPE_REF,   // A variable reference.
     AST_TYPE_LAMBDA, // An anonymous function definition.
-    AST_TYPE_ARG,    // A definition argument.
-    AST_TYPE_MAX = AST_TYPE_ARG,
+    AST_TYPE_EXC,   // An exception.
+    AST_TYPE_MAX = AST_TYPE_EXC,
 } ASTType;
 
 // An Abstract Syntax Tree.
@@ -60,12 +65,22 @@ ASTBoolData* ast_bool_data_init(int val);
 // Destroy an `ASTBoolData`.
 void ast_bool_data_destroy(ASTBoolData* bol);
 
-// A kind.
-typedef struct {
-    char* name;
-
+// A literal kind.
+typedef enum {
+    AST_LIT_KIND_BOOL,
+    AST_LIT_KIND_NUM,
+    AST_LIT_KIND_KIND,
+    AST_LIT_KIND_MAX = AST_LIT_KIND_KIND
 } ASTKindData;
 
+extern const char* ast_lit_kind_names[AST_LIT_KIND_MAX + 2];
+
+// Create a new `ASTKindData`.
+ASTKindData* ast_kind_data_init(ASTKindData);
+
+// Destroy an `ASTKindData`.
+void ast_kind_data_destroy(ASTKindData*);
+
 // An exception.
 typedef struct ASTEXCDATA {
     const char* msg; // The exception message.
@@ -120,26 +135,27 @@ ASTCallData* ast_call_data_init(size_t argc, AST** argv, AST* exp);
 // Destroy an `ASTCallData`.
 void ast_call_data_destroy(ASTCallData* call);
 
-// A variable definition. Associates a name with an expression.
+// A definition. Associates a name and kind with an expression.
 typedef struct {
     char* name;
+    AST* kind; // If NULL, assume `Any` kind.
     AST* exp;
-} ASTVDefData;
+} ASTDefData;
 
-// Create a new `ASTVDefData`.
-ASTVDefData* ast_vdef_data_init(char* name, AST* exp);
-// Destroy an `ASTVDefData`.
-void ast_vdef_data_destroy(ASTVDefData* vdef);
+// Create a new `ASTDefData`.
+ASTDefData* ast_def_data_init(char* name, AST* kind, AST* exp);
+// Destroy an `ASTDefData`.
+void ast_def_data_destroy(ASTDefData* vdef);
 
-// A variable reference.
+// A reference.
 typedef struct {
     char* to; // What the reference's to.
-} ASTVrefData;
+} ASTRefData;
 
-// Create a new `ASTVRefData`.
-ASTVrefData* ast_vref_data_init(char* to);
-// Destroy an `ASTVRefData`.
-void ast_vref_data_destroy(ASTVrefData* call);
+// Create a new `ASTRefData`.
+ASTRefData* ast_ref_data_init(char* to);
+// Destroy an `ASTRefData`.
+void ast_ref_data_destroy(ASTRefData* call);
 
 // A code block.
 typedef struct {
@@ -151,8 +167,6 @@ typedef struct {
 ASTBlockData* ast_block_data_init(AST** inside, size_t ln);
 // Destroy an `ASTBlockData`, recursively.
 void ast_block_data_destroy(ASTBlockData* block);
-// Destroy an `ASTBlockData`.
-void ast_block_data_destroy_psv(ASTBlockData* block);
 
 typedef struct {
     char* name; // Argument name.
@@ -166,4 +180,14 @@ void ast_arg_data_destroy(ASTArgData* arg);
 // Find the expression associated with a name in the nearest scope.
 AST* ast_find(Scope* scope, char* name);
 
+// A force operator.
+typedef struct {AST* body;} ASTForceData;
+ASTForceData* ast_force_data_init(AST* body);
+void ast_force_data_destroy(ASTForceData* force);
+
+// A preserve operator.
+typedef struct {AST* body;} ASTPreserveData;
+ASTPreserveData* ast_preserve_data_init(AST* body);
+void ast_preserve_data_destroy(ASTPreserveData* preserve);
+
 #endif

src/include/ast_print.h

@@ -14,17 +14,20 @@ void ast_num_print(ASTNumData*, int i);
 // Print an `ASTBoolData`.
 void ast_bool_print(ASTBoolData*, int i);
 
+// Print an `ASTKindData`.
+void ast_kind_print(ASTKindData*, int i);
+
 // Print an `ASTExecData`.
 void ast_exc_print(ASTExcData*, int i);
 
 // Print an `ASTCallData`.
 void ast_call_print(ASTCallData*, int i);
 
-// Print an `ASTVDefData`.
-void ast_vdef_print(ASTVDefData*, int depth);
+// Print an `ASTDefData`.
+void ast_def_print(ASTDefData*, int depth);
 
-// Print an `ASTVRefData`.
-void ast_vref_print(ASTVrefData*, int i);
+// Print an `ASTRefData`.
+void ast_ref_print(ASTRefData*, int i);
 
 // Print an `ASTBlockData`.
 void ast_block_print(ASTBlockData*, int i);
@@ -38,4 +41,9 @@ void ast_lambda_print(ASTLambdaData* arg, int i);
 // Print an `ASTBIFData`.
 void ast_bif_print(ASTBIFData* arg, int i);
 
+// Print an `ASTForceData`.
+void ast_force_print(ASTForceData* force, int i);
+
+// Print an `ASTPreserveData`.
+void ast_preserve_print(ASTPreserveData* preserve, int i);
 #endif

src/include/exec.h

@@ -12,14 +12,18 @@ AST* exec_exp(AST* ast, Scope* parent);
 AST* exec_block(AST* ast, Scope* parent);
 // Execute a call.
 AST* exec_call(AST* ast, Scope* parent);
-// Execute a variable definition.
-AST* exec_vdef(AST* ast, Scope* parent);
-// Execute a variable reference.
-AST* exec_vref(AST* ast, Scope* parent);
+// Execute a definition.
+AST* exec_def(AST* ast, Scope* parent);
+// Execute a reference.
+AST* exec_ref(AST* ast, Scope* parent);
 // Execute a function definition.
 AST* exec_fdef(AST* ast, Scope* parent);
 // Execute a lambda expression.
 AST* exec_lambda(size_t argc, AST** argv, AST* exp, Scope* parent);
+// Execute a force expression.
+AST* exec_force(AST* ast, Scope* parent);
+// Execute a preserve expression.
+AST* exec_preserve(AST* ast, Scope* parent);
 // Print the result of an execution.
 void exec_print(double n);
 

src/include/gc.h

@@ -2,6 +2,7 @@
 #define GC_H
 
 #include <stdlib.h>
+#include <stdbool.h>
 
 // The type a GC can refer to.
 typedef enum {

src/lexer.c

@@ -106,18 +106,17 @@ int yylex() {
     // Assign & consume current character.
     int c = *inp++;
 
+    if (c == '-' && *inp == '>' && inp++) { return RARROW; }
+    if (c == '<' && *inp == '-' && inp++) { return LARROW; }
+    if (c == '=' && *inp == '=' && inp++) { return DEQ; }
+    if (c == '=' && *inp != '=') { return EQ; }
+
     // Check for NUM.
     if (isdigit(c)) {
         yylval.fval = acc_float(c); // Set the token value.
         return NUM;
     }
 
-    if (c == '=') {
-        yylval.strval = acc_deq(c);
-        if (!strcmp(yylval.strval, "=")) return EQ;
-        if (!strcmp(yylval.strval, "==")) return DEQ;
-    }
-
     if (isalpha(c) || c == '_') {
         yylval.strval = acc_word(c);
 
@@ -143,10 +142,12 @@ int yylex() {
         case ';':  return EXPSEP;
         case '{':  return BLOCKS;
         case '}':  return BLOCKE;
-        // case '=':  return EQ;
         case '\\': return BACKSLASH;
         case '?':  return IF;
-        case ':':  return ELSE;
+        case ':':  return COLON;
+        case '$':  return STOP;
+        case '!':  return FORCE;
+        case '@':  return PRESERVE;
         default:   fprintf(stderr, "Unexpected character: %c\n", c);
     }
 

src/main.c

@@ -19,8 +19,8 @@ extern int yyparse();
 int main(int argc, char** argv) {
 
     if (argc - 1 && strlen(argv[1]) > 0 && (inp = argv[1]) && !yyparse()) {
-        log_dbg("Parsed successfully!\n");
-        ast_print(root);
+        // log_dbg("Parsed successfully!\n");
+        // ast_print(root);
         AST* eval = exec_start(root);
         ast_print(eval);
         // ast_destroy(eval);
@@ -54,7 +54,11 @@ int main(int argc, char** argv) {
             inp = ln->buf;
             if (yyparse() == 0) {
                 log_dbg("Parsed successfully!\n");
-            } else printf("Parse error.\n");
+            } else {
+                printf("Parse error.\n");
+                dstr_destroy(ln);
+                continue;
+            }
 
 #ifdef DBG
             ast_print(root);

test/test_ast.c

@@ -17,7 +17,7 @@ void test_ast_num() {
 }
 
 void test_ast_call() {
-    AST** argv = malloc(2*sizeof(AST*));
+    AST** argv = malloc(2 * sizeof(AST*));
     argv[0] = ast_init(AST_TYPE_NUM, ast_num_data_init(1.0));
     argv[1] = ast_init(AST_TYPE_NUM, ast_num_data_init(2.0));
 
@@ -37,23 +37,8 @@ void test_ast_call() {
     ast_destroy(ast);
 }
 
-void test_ast_vref() {
-    char* s = malloc(2);
-    strcpy(s, "x");
-    ASTVrefData* vref = ast_vref_data_init(s);
-    AST* ast = ast_init(AST_TYPE_VREF, vref);
-
-    TEST_ASSERT_EQUAL(AST_TYPE_VREF, ast->type);
-    ASTVrefData data = *(ASTVrefData*)ast->data;
-    TEST_ASSERT_EQUAL_STRING("x", data.to);
-
-    //ast_destroy(ast);
+// ast_destroy(ast);
 }
 
 int main() {
     UNITY_BEGIN();
-    RUN_TEST(test_ast_num);
-    //RUN_TEST(test_ast_call);
-    //RUN_TEST(test_ast_vref);
-    return UNITY_END();
-}

type_notes.md

@@ -0,0 +1,31 @@
+n: Int = 3
+
+- 'Int': integer constructor
+- '3': integer literal
+
+v: Vec(3, Int) = <1, 2, 3>
+
+Point: Struct = { x: Int, y: Int }
+
+p: Point = { .x = 1, .y = 2 }
+p.x + p.y
+
+VecOf(n: Int, t: Type): Type = Vec(n, t)
+strings: VecOf(3, Str) = <"Hello", ",", " world.">
+
+f(g) = g(2)
+
+g(n: Int): Int = n * 2
+g: Lambda(Int, Int) = \(n: Int):Int n * 2
+
+Int, Vec, Str
+
+f(g: \(Int):Int ):Int = g(2)
+f(g: Lambda(Int, Int)): Int = g(2)
+
+f: Lambda(Int, Str, Str) = \(s1: Str, s2: Str) length(s) + length(s2)
+
+Bad: Type = if Until.time() % 2 == 0 Str Int
+
+- Types are code.
+- All types inherit from `Type` (the type of `Type` is `Type`).