Updated README.md.

NOTE: changed versioning system slightly.

README.md

@@ -1,20 +1,20 @@
 # SCL: Simple CAS Language
 
-Version v1.0-beta
+*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 basic 4-function calculator with order
-of operations and local variables. The codebase is about 1,400 lines of C,
-including a parser, interpreter, and runtime. It uses a linked environment
-scoping model.
+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
+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
 ```
@@ -22,75 +22,44 @@ 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) = 2x
-> n = 3
-> f(n)
-= 6
-```
-
-As SCL uses a linked environment model for scope, arguments are passed by
-reference by default. If you would like to pass by value (i.e., a copy) you may
-use the syntax:
-
-```scl
-> f(x) = x = 1
-> n = 4
-> f($n) # Pass a copy of n.
-= 1
-> n
+> (\(x) 2 * x)(5)
+= 10
+> f(g) g(2)
+> f(\(x) 2 * x)
 = 4
-> f(n) # Pass a reference to n.
-= 1
-> n
-> 1
 ```
 
-Symbolic algebra is done in the following manner:
+Here's a simple factorial function, using recursion:
 
 ```scl
-> f(x) = x^4
-> diff(f, x:sym, 2)
-= 12x^2
+> factorial(n) {
+>   if (n == 0) { 1 }
+>   else { n * factorial(n - 1) }
+> }
 ```
 
-SCL will dynamically decide on types, but you can state them explicitly as
-well:
+SCL's syntax is quite flexible. The above function could be more concisely
+written as:
 
 ```scl
-> f(x: int): int = 2x
-> f(3)
-= 6
-> f(3.1)
-! Traceback:
-! In call to `f(x: int): int`:
-! TypeError (58): Argument `x` must be of type `int`.
-```
-
-Variables can be defined, with several attributes:
-
-```scl
-> a = 1             // Interpret type automatically.
-> b:int = 1         // Must be int.
-> c:const:int = 1   // Constant: value can never change.
-> x:sym             // Treated symbolicaly.
+> factorial(n) ? n == 0 1 n * factorial(n - 1)
 ```

TODO.md

@@ -1,5 +1,7 @@
-1. Differentiate parameters and arguments -- params for function definitions,
-arguments for function calls
+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
+message for special exceptions e.g. exit().
 
 Change editor to GNU Readline.
 Make variables persist through lines in the editor.

examples/function.scl

@@ -1,3 +1,2 @@
-f(n) 2 * n
-
-f(5)
+apply(f, x) f(x)
+apply(\(x) x + 1, 2)

src/ast.c

@@ -40,6 +40,7 @@ void ast_destroy(AST* ast) {
 
     switch (ast->type) {
         case AST_TYPE_NUM:    ast_num_data_destroy(ast->data); break;
+        case AST_TYPE_BOOL:   ast_bool_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;
@@ -66,6 +67,16 @@ ASTNumData* ast_num_data_init(double val) {
 
 void ast_num_data_destroy(ASTNumData* num) { free(num); }
 
+ASTBoolData* ast_bool_data_init(int val) {
+    talloc(ASTBoolData, bol);
+
+    *bol = val;
+
+    return bol;
+}
+
+void ast_bool_data_destroy(ASTBoolData* bol) { free(bol); }
+
 ASTExcData* ast_exc_data_init(const char* msg, AST* trace) {
     ASTExcData* data = malloc(sizeof(ASTExcData));
     data->msg = msg;

src/ast_print.c

@@ -8,6 +8,7 @@
 static char* asttype_names[] = {
     [AST_TYPE_CALL] = "FUNC CALL",
     [AST_TYPE_NUM] = "NUMBER",
+    [AST_TYPE_BOOL] = "BOOLEAN",
     [AST_TYPE_VREF] = "VAR REFERENCE",
     [AST_TYPE_VDEF] = "VAR DEFINITION",
     [AST_TYPE_BLOCK] = "BLOCK",
@@ -28,12 +29,17 @@ void ast_print_i(AST* ast, int i) {
 
     INDENT_TITLE("AST", ast);
     INDENT_FIELD("type", "%s", asttype_names[ast->type]);
-    // INDENT_FIELD("scope", "%p", ast->scope);
     INDENT_FIELD_EXT_NONL_START("data");
     switch (ast->type) {
         case AST_TYPE_NUM:
             printf("%s  %lf\n", INDENT_spacing->buf, *(ASTNumData*)ast->data);
             break;
+        case AST_TYPE_BOOL:
+            printf(
+                "%s  %s\n", INDENT_spacing->buf,
+                *(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;
@@ -57,6 +63,14 @@ void ast_num_print(ASTNumData* data, int i) {
     INDENT_END;
 }
 
+void ast_bool_print(ASTBoolData* data, int i) {
+    INDENT_BEGIN(i);
+
+    INDENT_FIELD("data", "%s", *data ? "true" : "false");
+
+    INDENT_END;
+}
+
 void ast_exc_print(ASTExcData* data, int i) {
     INDENT_BEGIN(i);
 

src/builtin.c

@@ -1,10 +1,10 @@
-#include "include/builtin.h"
-#include "include/ast.h"
-#include "include/exec.h"
-#include "include/util.h"
 #include <stdarg.h>
 #include <stdio.h>
 
+#include "include/ast.h"
+#include "include/builtin.h"
+#include "include/exec.h"
+
 AST* builtin_sum(size_t argc, AST** argv, Scope* parent) {
     ASTNumData total = 0;
 
@@ -28,7 +28,8 @@ AST* builtin_sum(size_t argc, AST** argv, Scope* parent) {
 }
 
 AST* builtin_sub(size_t argc, AST** argv, Scope* parent) {
-    log_dbg("Got here");
+    if (argc <= 0) return ast_init(AST_TYPE_NUM, ast_num_data_init(0));
+
     AST* first = exec_exp(*argv, parent);
     if (first->type == AST_TYPE_EXC)
         return ast_init(
@@ -63,7 +64,8 @@ AST* builtin_sub(size_t argc, AST** argv, Scope* parent) {
 }
 
 AST* builtin_mul(size_t argc, AST** argv, Scope* parent) {
-    log_dbg("Got here");
+    if (argc <= 0) return ast_init(AST_TYPE_NUM, ast_num_data_init(0));
+
     AST* first = exec_exp(*argv, parent);
     if (first->type == AST_TYPE_EXC)
         return ast_init(
@@ -98,7 +100,8 @@ AST* builtin_mul(size_t argc, AST** argv, Scope* parent) {
 }
 
 AST* builtin_div(size_t argc, AST** argv, Scope* parent) {
-    log_dbg("Got here");
+    if (argc <= 0) return ast_init(AST_TYPE_NUM, ast_num_data_init(0));
+
     AST* first = exec_exp(*argv, parent);
     if (first->type == AST_TYPE_EXC)
         return ast_init(
@@ -131,3 +134,77 @@ AST* builtin_div(size_t argc, AST** argv, Scope* parent) {
 
     return ast_init(AST_TYPE_NUM, ast_num_data_init(total));
 }
+
+AST* builtin_die(size_t argc, AST** argv, Scope* parent) {
+    return ast_init(AST_TYPE_EXC, ast_exc_data_init("8", NULL));
+}
+
+AST* builtin_if(size_t argc, AST** argv, Scope* parent) {
+    if (argc != 3)
+        return ast_init(
+            AST_TYPE_EXC,
+            ast_exc_data_init("If invoked with too few args.", NULL)
+        );
+
+    AST* pred = exec_exp(argv[0], parent);
+    AST* body = argv[1];
+    AST* alt = argv[2];
+
+    if (pred->type != AST_TYPE_BOOL) {
+        if (pred->type == AST_TYPE_EXC) {
+            return ast_init(
+                AST_TYPE_EXC, ast_exc_data_init("if touched an error", pred)
+            );
+        } else {
+            return ast_init(
+                AST_TYPE_EXC,
+                ast_exc_data_init("if works on booleans idiot", NULL)
+            );
+        }
+    }
+
+    if (*(ASTBoolData*)pred->data) return exec_exp(body, parent);
+    else return exec_exp(alt, parent);
+}
+
+AST* builtin_eq(size_t argc, AST** argv, Scope* parent) {
+    if (argc < 1) return ast_init(AST_TYPE_EXC, ast_exc_data_init("bad", NULL));
+    else if (argc == 1) return ast_init(AST_TYPE_BOOL, ast_bool_data_init(1));
+
+    AST* first = exec_exp(argv[0], parent);
+    ASTType type = first->type;
+
+    AST* second = exec_exp(argv[1], parent);
+    if (first->type == AST_TYPE_EXC)
+        return ast_init(
+            AST_TYPE_EXC, ast_exc_data_init("first was bad", first)
+        );
+    if (second->type == AST_TYPE_EXC)
+        return ast_init(
+            AST_TYPE_EXC, ast_exc_data_init("second was bad", second)
+        );
+
+    if (second->type != type)
+        return ast_init(
+            AST_TYPE_EXC,
+            ast_exc_data_init("apples and oranges or something idk", NULL)
+        );
+
+    // Later when I put together an anctual type system I'll have this
+    // delegated to each type. For now this works.
+
+    switch (type) {
+        case AST_TYPE_NUM:
+            if (*(ASTNumData*)first->data == *(ASTNumData*)second->data)
+                return ast_init(AST_TYPE_BOOL, ast_bool_data_init(1));
+            else return ast_init(AST_TYPE_BOOL, ast_bool_data_init(0));
+        case AST_TYPE_BOOL:
+            if (*(ASTNumData*)first->data == *(ASTNumData*)second->data)
+                return ast_init(AST_TYPE_BOOL, ast_bool_data_init(1));
+            else return ast_init(AST_TYPE_BOOL, ast_bool_data_init(0));
+        default:
+            return ast_init(
+                AST_TYPE_BOOL, ast_bool_data_init(0)
+            ); // Can't equate nonprimatives. I think. Maybe.
+    }
+}

src/dlist.c

@@ -1,9 +1,9 @@
-#include "include/dlist.h"
-#include "include/util.h"
-
 #include <stddef.h>
 #include <stdio.h> // IWYU pragma: keep. Req by util macros.
 
+#include "include/dlist.h"
+#include "include/util.h"
+
 DList* dlist_init(void) {
     DList* dlist = malloc(sizeof(DList));
 

src/exec.c

@@ -38,6 +38,10 @@ AST* exec_exp(AST* ast, Scope* parent) {
             return ast_init(
                 AST_TYPE_NUM, ast_num_data_init(*(ASTNumData*)ast->data)
             );
+        case AST_TYPE_BOOL:
+            return ast_init(
+                AST_TYPE_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_FDEF:   return exec_fdef(ast, parent);
@@ -107,7 +111,8 @@ AST* exec_vref(AST* ast, Scope* parent) {
         return ast_init(AST_TYPE_EXC, ast_exc_data_init(msg, NULL));
     }
 
-    return exec_exp(found, ast->scope);
+    // return exec_exp(found, ast->scope);
+    return found;
 }
 
 AST* exec_fdef(AST* ast, Scope* parent) {
@@ -124,7 +129,7 @@ AST* exec_lambda(size_t argc, AST** argv, AST* exp, Scope* parent) {
     ASTLambdaData* lambda = (ASTLambdaData*)exp->data;
     for (int i = 0; i < argc; i++) {
         char* key = ((ASTArgData*)lambda->parv[i]->data)->name;
-        AST* val = argv[i];
+        AST* val = exec_exp(argv[i], parent);
         scope_add(callscope, key, val);
     }
 

src/grammar.y

@@ -28,6 +28,12 @@
 
 %define parse.error verbose
 
+%token BOOLT // Boolean true (TRUE or T).
+%token BOOLF // Boolean false (FALSE or F).
+
+%token IF // if or ?.
+%token ELSE // else or :.
+
 %token BLOCKS // Block start {.
 %token BLOCKE // Block end }.
 
@@ -36,6 +42,7 @@
 %token SEP // Seperator ,.
 
 %token EQ // Equals =.
+%token DEQ // Double equals ==.
 
 %token EXPSEP // Expression seperator ;.
 
@@ -129,6 +136,46 @@ exp:
     // Number.
     NUM { $$ = ast_init(AST_TYPE_NUM, ast_num_data_init($1)); }
 
+    | BOOLT { $$ = ast_init(AST_TYPE_BOOL, ast_bool_data_init(1)); }
+    | BOOLF { $$ = ast_init(AST_TYPE_BOOL, ast_bool_data_init(0)); }
+
+    | exp DEQ exp {
+        AST** argv = calloc(2, sizeof(AST*));
+        argv[0] = $1;
+        argv[1] = $3;
+
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
+            2,
+            argv,
+            ast_init(AST_TYPE_BIF, ast_bif_data_init(builtin_eq))
+        ));
+    }
+
+    | IF exp exp exp {
+        AST** argv = calloc(3, sizeof(AST*));
+        argv[0] = $2;
+        argv[1] = $3;
+        argv[2] = $4;
+
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
+            3,
+            argv,
+            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;
+        argv[1] = $3;
+        argv[2] = $5;
+
+        $$ = ast_init(AST_TYPE_CALL, ast_call_data_init(
+            3,
+            argv,
+            ast_init(AST_TYPE_BIF, ast_bif_data_init(builtin_if))
+        ));
+    }
+
     // Variable reference.
     | WORD {
         $$ = ast_init(AST_TYPE_VREF, ast_vref_data_init($1));
@@ -158,6 +205,17 @@ exp:
         ));
     }
 
+    // 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 {
         size_t parc = $3->ln;

src/include/ast.h

@@ -7,11 +7,12 @@
 // The type of an `AST`.
 typedef enum {
     // Primitive types.
-    AST_TYPE_NUM, // A number (float).
-    AST_TYPE_STR, // A string
-    AST_TYPE_INT, // An integer.
-    AST_TYPE_SYM, // A symbol.
-    AST_TYPE_EXC, // Exception.
+    AST_TYPE_NUM,  // A number (float).
+    AST_TYPE_STR,  // A string
+    AST_TYPE_INT,  // An integer.
+    AST_TYPE_BOOL, // A boolean.
+    AST_TYPE_SYM,  // A symbol.
+    AST_TYPE_EXC,  // Exception.
 
     // Collection types:
     AST_TYPE_VEC,  // A vector (fixed size, fixed type).
@@ -51,6 +52,14 @@ ASTNumData* ast_num_data_init(double val);
 // Destroy an `ASTNumData`.
 void ast_num_data_destroy(ASTNumData* num);
 
+// A boolean.
+typedef int ASTBoolData;
+
+// Create a new `ASTBoolData`.
+ASTBoolData* ast_bool_data_init(int val);
+// Destroy an `ASTBoolData`.
+void ast_bool_data_destroy(ASTBoolData* bol);
+
 // An exception.
 typedef struct ASTEXCDATA {
     const char* msg; // The exception message.
@@ -96,8 +105,8 @@ void ast_lambda_data_destroy(ASTLambdaData*);
 
 // A call.
 typedef struct {
-    ARGS;        // The arguments the call is made with.
-    AST* exp;     // The expression the call is to.
+    ARGS;     // The arguments the call is made with.
+    AST* exp; // The expression the call is to.
 } ASTCallData;
 
 // Create a new `ASTCallData`.

src/include/ast_print.h

@@ -11,6 +11,9 @@ void ast_print_i(AST* ast, int i);
 // Print an `ASTNumData`.
 void ast_num_print(ASTNumData*, int i);
 
+// Print an `ASTBoolData`.
+void ast_bool_print(ASTBoolData*, int i);
+
 // Print an `ASTExecData`.
 void ast_exc_print(ASTExcData*, int i);
 

src/include/builtin.h

@@ -2,6 +2,7 @@
 #define BUILTIN_H
 
 #include "ast.h"
+#include <stddef.h>
 
 // Sum some nums.
 AST* builtin_sum(size_t argc, AST** argv, Scope* parent);
@@ -15,6 +16,15 @@ AST* builtin_mul(size_t argc, AST** argv, Scope* parent);
 // Divide nums.
 AST* builtin_div(size_t argc, AST** argv, Scope* parent);
 
+// Die.
+AST* builtin_die(size_t argc, AST** argv, Scope* parent);
+
+// If statement.
+AST* builtin_if(size_t argc, AST** argv, Scope* parent);
+
+// Equality.
+AST* builtin_eq(size_t argc, AST** argv, Scope* parent);
+
 struct builtin_data {
     char* name;
     AST* (*fn)(size_t argc, AST** argv, Scope* parent);
@@ -25,6 +35,9 @@ static struct builtin_data BUILTIN_FNS[] = {
     { "sub", builtin_sub },
     { "mul", builtin_mul },
     { "div", builtin_div },
+    { "die", builtin_die },
+    {"_if", builtin_if},
+    {"eq", builtin_eq},
 };
 #define BUILTIN_FNS_LN (arrln(BUILTIN_FNS))
 

src/lexer.c

@@ -3,6 +3,7 @@
 #include <limits.h>
 #include <math.h>
 #include <stdio.h>
+#include <string.h>
 
 #include "include/dstr.h"
 #include "include/lexer.h"
@@ -72,7 +73,20 @@ double acc_float(int c) {
 
 char* acc_word(int c) {
     Dstr* val = dstr_init();
-    while (isalpha(*inp)) {
+    while (isalpha(*inp) || *inp == '_') {
+        dstr_appendch(val, *(inp - 1));
+        inp++;
+    }
+    dstr_appendch(val, *(inp - 1));
+
+    char* ret = val->buf;
+    dstr_destroypsv(val);
+    return ret;
+}
+
+char* acc_deq(int c) {
+    Dstr* val = dstr_init();
+    while (*inp == '=') {
         dstr_appendch(val, *(inp - 1));
         inp++;
     }
@@ -98,8 +112,22 @@ int yylex() {
         return NUM;
     }
 
-    if (isalpha(c)) {
+    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);
+
+        if (!strcmp(yylval.strval, "TRUE") || !strcmp(yylval.strval, "T"))
+            return BOOLT;
+        if (!strcmp(yylval.strval, "FALSE") || !strcmp(yylval.strval, "F"))
+            return BOOLF;
+        if (!strcmp(yylval.strval, "if")) return IF;
+        if (!strcmp(yylval.strval, "else")) return ELSE;
+
         return WORD;
     }
 
@@ -115,8 +143,10 @@ int yylex() {
         case ';':  return EXPSEP;
         case '{':  return BLOCKS;
         case '}':  return BLOCKE;
-        case '=':  return EQ;
+        // case '=':  return EQ;
         case '\\': return BACKSLASH;
+        case '?':  return IF;
+        case ':':  return ELSE;
         default:   fprintf(stderr, "Unexpected character: %c\n", c);
     }
 

src/main.c

@@ -62,6 +62,13 @@ int main(int argc, char** argv) {
 
             AST* eval = exec_start(root);
             ast_print(eval);
+            // Awful hack to exit when die() is called, until proper exception
+            // handling is implemented. TODO TODO TODO PLSFIX.
+            if (eval->type == AST_TYPE_EXC &&
+                ((ASTExcData*)eval->data)->msg[0] == '8') {
+                gc_hack_free();
+                exit(1);
+            }
             gc_hack_free();
         }