initial support for nil, make-list

unfinished, but usable.. still 0 is false in libs and code

Readme.md

@@ -4,7 +4,7 @@
 
 ### TODO
 - test whether AIG,,,10 csv row is parsed
-- support for (), nil, t
+- support for (), nil, t, in lsp code replace 0 by nil in logicals
 - print-table
 - download 10 years of data from api.nasdaq.com into test dir
 - documentation

debug.lsp

@@ -24,4 +24,9 @@
 
 (print (string-lpad "lpad" 10 "x"))
 
+(print nil)
+(print ())
+
+(print (make-list 5))
+
 (print "Debug ends")

ml.cpp

@@ -30,7 +30,6 @@
 #define INVALID_ORDER "cannot order expression"
 #define BAD_CAST "cannot cast"
 #define ATOM_NOT_DEFINED "atom not defined"
-#define EVAL_EMPTY_LIST "evaluated empty list"
 #define INTERNAL_ERROR "internal virtual machine error"
 #define INDEX_OUT_OF_RANGE "index out of range"
 #define MALFORMED_PROGRAM "malformed program"
@@ -40,6 +39,7 @@
 #define INT_TYPE "int"
 #define FLOAT_TYPE "float"
 #define UNIT_TYPE "unit"
+#define NIL_TYPE "nil"
 #define FUNCTION_TYPE "function"
 #define ATOM_TYPE "atom"
 #define QUOTE_TYPE "quote"
@@ -93,6 +93,12 @@ MlValue MlValue::string(const std::string &s) {
 	return result;
 }
 
+MlValue MlValue::nil() {
+	MlValue result;
+	result.type = NIL;
+	return result;
+}
+
 // Construct a lambda function
 MlValue::MlValue(const std::vector<MlValue> &params, MlValue ret, MlEnvironment const &env) : type(LAMBDA) {
 	// We store the params and the result in the list member
@@ -162,7 +168,7 @@ bool MlValue::is_number() const {
 
 // Get the "truthy" boolean value of this value.
 bool MlValue::as_bool() const {
-	return *this != MlValue(0);
+	return type != NIL && *this != MlValue(0);	// TODO remove 0 as false
 }
 
 // Get this item's integer value
@@ -281,6 +287,8 @@ bool MlValue::operator==(MlValue other) const {
 			// The values for quotes are stored in the
 			// first slot of the list member.
 			return list[0] == other.list[0];
+		case NIL:
+			return other.type == NIL;
 		default:
 			return true;
 	}
@@ -516,6 +524,8 @@ std::string MlValue::get_type_name() {
 			return FUNCTION_TYPE;
 		case UNIT:
 			return UNIT_TYPE;
+		case NIL:
+			return NIL_TYPE;
 		default:
 			// We don't know the name of this type.
 			// This isn't the users fault, this is just unhandled.
@@ -553,6 +563,8 @@ std::string MlValue::display() const {
 			return "<" + str + " at " + to_string(long(stack_data.b)) + ">";
 		case UNIT:
 			return "@";
+		case NIL:
+			return "nil";
 		default:
 			// We don't know how to display whatever type this is.
 			// This isn't the users fault, this is just unhandled.
@@ -594,6 +606,8 @@ std::string MlValue::debug() const {
 			return "<" + str + " at " + to_string(long(stack_data.b)) + ">";
 		case UNIT:
 			return "@";
+		case NIL:
+			return "nil";
 		default:
 			// We don't know how to debug whatever type this is.
 			// This isn't the users fault, this is just unhandled.
@@ -621,8 +635,7 @@ MlError::~MlError() {
 }
 
 std::string MlError::description() {
-	return "error: the expression `" + cause->debug() + "` failed in scope " + to_string(env) + " with message \"" +
-	       msg + "\"";
+	return "error: the expression `" + cause->debug() + "` failed in scope " + to_string(env) + " with message \"" + msg + "\"";
 }
 
 void MlEnvironment::combine(MlEnvironment const &other) {
@@ -657,9 +670,7 @@ MlValue MlValue::apply(std::vector<MlValue> args, MlEnvironment &env) {
 			// Get the list of parameter atoms
 			params = list[0].list;
 			if (params.size() != args.size())
-				throw MlError(MlValue(args), env, args.size() > params.size() ?
-								  TOO_MANY_ARGS : TOO_FEW_ARGS
-				);
+				throw MlError(MlValue(args), env, args.size() > params.size() ? TOO_MANY_ARGS : TOO_FEW_ARGS);
 
 			// Get the captured scope from the lambda
 			e = lambda_scope;
@@ -701,7 +712,7 @@ MlValue MlValue::eval(MlEnvironment &env) {
 			return env.get(str);
 		case LIST:
 			if (list.size() < 1)
-				throw MlError(*this, env, EVAL_EMPTY_LIST);
+				return MlValue::nil();
 
 			args = std::vector<MlValue>(list.begin() + 1, list.end());
 
@@ -747,6 +758,7 @@ MlValue parse(std::string &s, int &ptr) {
 
 	if (s == "") {
 		return MlValue();
+
 	} else if (s[ptr] == '\'') {
 		// If this is a quote
 		ptr++;
@@ -807,6 +819,7 @@ MlValue parse(std::string &s, int &ptr) {
 		}
 
 		return MlValue::string(x);
+
 	} else if (s[ptr] == '@') {
 		ptr++;
 		skip_whitespace(s, ptr);
@@ -822,7 +835,11 @@ MlValue parse(std::string &s, int &ptr) {
 		std::string x = s.substr(ptr, n);
 		ptr += n;
 		skip_whitespace(s, ptr);
+		if (x == "nil")
+			return MlValue::nil();
+		else
 			return MlValue::atom(x);
+
 	} else {
 		throw std::runtime_error(MALFORMED_PROGRAM);
 	}
@@ -1765,7 +1782,7 @@ int main(int argc, const char **argv) {
 	try {
 		load_std_lib(env);
         // for xcode profiling
-        // run(read_file_contents("/Users/vaclavt/Development/mlisp/tests/test.lsp"), env);
+        run(read_file_contents("/Users/vaclavt/Development/mlisp/tests/test.lsp"), env);
 
 		if (argc == 1 || (argc == 2 && std::string(argv[1]) == "-i"))
 			repl(env);

ml.h

@@ -98,6 +98,9 @@ public:
     // Construct a string
     static MlValue string(const std::string &s);
 
+    // Construct a nil
+    static MlValue nil();
+
     // Construct a lambda function
     MlValue(const std::vector<MlValue> &params, MlValue ret, MlEnvironment const &env);
 
@@ -197,7 +200,8 @@ private:
 	STRING,
 	LAMBDA,
 	BUILTIN,
-	UNIT
+	UNIT,
+	NIL
     } type;
 
     union {

stdlib/stdlib.lsp

@@ -69,6 +69,19 @@
             0)
     ))
 
+(defun make-list-of (size val)
+    (do
+        (define lst '())
+        (define i 0)
+        (while (< i size)
+            (define lst (push lst val))
+            (define i (inc i)))
+        lst
+    ))
+
+(defun make-list (size)
+    (make-list-of size nil))
+
 
 ; quicksort
 (defun quick-sort-by (l cmp)

tests/test.lsp

@@ -14,6 +14,9 @@
 (print "(member '(1 2 3) 3:" (member '(1 2 3) 3))
 (print "(member '(1 2 3) 30:" (member '(1 2 3) 30))
 
+(print "(make-list 3) :" (make-list 3))
+(print "(make-list-of 3) :" (make-list-of 3 999))
+
 
 (defun fact (n)
    (if (<= n 1)
@@ -45,7 +48,7 @@
 (print "sorted: " (quick-sort '(1 2 3 4 5 6 7 8 9 10)))
 (print "sorted by: " (quick-sort-by '(10 9 8 7 6 5 4 3 2 1) (lambda (a b) (> a b)) ))
 (print "sorted by: " (quick-sort-by '(1 2 3 4 5 6 7 8 9 10) (lambda (a b) (> a b)) ))
-(print "sorted by: " (quick-sort-by '(1 2 3 4 5 6 7 8 9 10) (lambda (a b) (< a b)) ))
+(print "sorted by desc: " (quick-sort-by '(1 2 3 4 5 6 7 8 9 10) (lambda (a b) (< a b)) ))