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Some more type safety. (0.8.0)

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This commit is contained in:
Johannes Findeisen 2025-09-28 15:24:09 +02:00
commit a1a5d9fd6a
4 changed files with 276 additions and 15 deletions
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2
CMakeLists.txt
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@ -1,5 +1,5 @@
cmake_minimum_required(VERSION 3.16)
project(fun VERSION 0.7.4 LANGUAGES C)
project(fun VERSION 0.8.0 LANGUAGES C)
set(CMAKE_C_STANDARD 11)
set(CMAKE_C_STANDARD_REQUIRED ON)

72
examples/type_safety.fun Normal file
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@ -0,0 +1,72 @@
#!/usr/bin/env fun
/**
* This file is part of the Fun programming language.
* https://hanez.org/project/fun/
*
* Copyright 2025 Johannes Findeisen <you@hanez.org>
* Licensed under the terms of the ISC license.
* https://opensource.org/license/isc-license-txt
*/
// Type Safety demonstration in Fun
print("== Dynamic variable (untyped) ==")
x = 100
print(typeof(x)) // -> "Number"
print(x) // -> 100
x = "hello"
print(typeof(x)) // -> "String"
print(x) // -> "hello"
print("")
print("== Typed variables remain type-stable ==")
// Strings must always be strings
string s = "hello"
print(typeof(s)) // -> "String"
print(s) // -> "hello"
// s = 42 // Uncomment to see runtime TypeError: expected String
// Booleans are Numbers constrained to 0 or 1 (clamped)
boolean flag = 0
print(typeof(flag)) // -> "Number"
print(flag) // -> 0
flag = 2 // will be clamped to 1
print(flag) // -> 1
// flag = "no" // Uncomment to see runtime TypeError: expected Number for boolean
// number is a signed 64-bit integer and must remain Number
number n = 123
print(typeof(n)) // -> "Number"
n = 456
print(n) // -> 456
// n = "oops" // Uncomment to see runtime TypeError: expected Number
print("")
print("== Integer width clamping ==")
// Signed 8-bit: range [-128..127]
int8 si = 130 // clamps to 127
print(si) // -> 127
si = -200 // clamps to -128
print(si) // -> -128
// Unsigned 8-bit: range [0..255]
uint8 u = 255
print(u) // -> 255
u = 300 // clamps to 255
print(u) // -> 255
// u = "bad" // Uncomment to see runtime TypeError: expected Number
print("")
print("== Nil-typed variables must stay Nil ==")
nil nn = nil
print(typeof(nn)) // -> "Nil"
// nn = 0 // Uncomment to see runtime TypeError: expected Nil
print("")
print("Done. Uncomment lines above to see type errors in action.")

21
examples/type_safety_fails.fun Normal file
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@ -0,0 +1,21 @@
#!/usr/bin/env fun
/**
* This file is part of the Fun programming language.
* https://hanez.org/project/fun/
*
* Copyright 2025 Johannes Findeisen <you@hanez.org>
* Licensed under the terms of the ISC license.
* https://opensource.org/license/isc-license-txt
*/
print("Reassigning typed variables to another type should fail")
string s = "hello"
print(typeof(s)) // -> "String"
print(s) // -> "hello"
print("Now trying to assign a number to a string variable...")
s = 42 // Runtime TypeError: expected String (assignment rejected)
print("This line will not execute due to the type error")

194
src/parser.c
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@ -62,6 +62,14 @@ static int g_err_col = 0;
/* ---- compiler-generated temporary counter ---- */
static int g_temp_counter = 0;
/* Declared type metadata encoding in types[]:
0 = dynamic/untyped;
positive/negative 8/16/32/64 = integers (negative means signed);
TYPE_META_STRING/BOOLEAN/NIL mark non-integer enforced types. */
#define TYPE_META_STRING 10001
#define TYPE_META_BOOLEAN 10002
#define TYPE_META_NIL 10003
static void parser_fail(size_t pos, const char *fmt, ...) {
g_has_error = 1;
g_err_pos = pos;
@ -1767,6 +1775,17 @@ static void parse_simple_statement(Bytecode *bc, const char *src, size_t len, si
int decl_signed = (is_s8 || is_s16 || is_s32 || is_s64) ? 1 : 0;
/* store decl bits with sign encoded: negative means signed (number is signed 64-bit) */
if (decl_signed) decl_bits = -decl_bits;
/* declared type metadata: integers use decl_bits; string/boolean/nil use special markers */
int decl_meta = decl_bits;
if (is_string) {
decl_meta = TYPE_META_STRING;
} else if (is_boolean) {
decl_meta = TYPE_META_BOOLEAN;
} else if (is_nil) {
decl_meta = TYPE_META_NIL;
}
free(name);
/* read variable name */
@ -1785,12 +1804,12 @@ static void parse_simple_statement(Bytecode *bc, const char *src, size_t len, si
if (existing >= 0) lidx = existing;
else lidx = local_add(varname);
if (lidx >= 0) {
g_locals->types[lidx] = decl_bits; /* negative = signed, positive = unsigned width, 0 = non-integer */
g_locals->types[lidx] = decl_meta; /* encoding: ±bits for integers; TYPE_META_* for non-integer enforced types; 0 = dynamic */
}
} else {
gi = sym_index(varname);
if (gi >= 0) {
G.types[gi] = decl_bits;
G.types[gi] = decl_meta;
}
}
free(varname);
@ -1802,11 +1821,87 @@ static void parse_simple_statement(Bytecode *bc, const char *src, size_t len, si
parser_fail(local_pos, "Expected initializer expression after '='");
return;
}
/* clamp if integer type was declared */
int abs_bits = decl_bits < 0 ? -decl_bits : decl_bits;
if (abs_bits > 0) {
bytecode_add_instruction(bc, (decl_bits < 0) ? OP_SCLAMP : OP_UCLAMP, abs_bits);
/* Enforce declared type on initializer */
if (decl_meta == TYPE_META_STRING) {
/* expect String */
bytecode_add_instruction(bc, OP_DUP, 0);
bytecode_add_instruction(bc, OP_TYPEOF, 0);
int ciExp = bytecode_add_constant(bc, make_string("String"));
bytecode_add_instruction(bc, OP_LOAD_CONST, ciExp);
bytecode_add_instruction(bc, OP_EQ, 0);
int j_to_error = bytecode_add_instruction(bc, OP_JUMP_IF_FALSE, 0);
int j_skip_err = bytecode_add_instruction(bc, OP_JUMP, 0);
/* error block */
bytecode_set_operand(bc, j_to_error, bc->instr_count);
{
int ciMsg = bytecode_add_constant(bc, make_string("TypeError: expected String"));
bytecode_add_instruction(bc, OP_LOAD_CONST, ciMsg);
bytecode_add_instruction(bc, OP_PRINT, 0);
bytecode_add_instruction(bc, OP_HALT, 0);
}
bytecode_set_operand(bc, j_skip_err, bc->instr_count);
} else if (decl_meta == TYPE_META_BOOLEAN) {
/* expect Number then clamp to 1 bit (unsigned) */
bytecode_add_instruction(bc, OP_DUP, 0);
bytecode_add_instruction(bc, OP_TYPEOF, 0);
int ciNum = bytecode_add_constant(bc, make_string("Number"));
bytecode_add_instruction(bc, OP_LOAD_CONST, ciNum);
bytecode_add_instruction(bc, OP_EQ, 0);
int j_to_error = bytecode_add_instruction(bc, OP_JUMP_IF_FALSE, 0);
int j_skip_err = bytecode_add_instruction(bc, OP_JUMP, 0);
bytecode_set_operand(bc, j_to_error, bc->instr_count);
{
int ciMsg = bytecode_add_constant(bc, make_string("TypeError: expected Number for boolean"));
bytecode_add_instruction(bc, OP_LOAD_CONST, ciMsg);
bytecode_add_instruction(bc, OP_PRINT, 0);
bytecode_add_instruction(bc, OP_HALT, 0);
}
bytecode_set_operand(bc, j_skip_err, bc->instr_count);
/* clamp to 0/1 */
bytecode_add_instruction(bc, OP_UCLAMP, 1);
} else if (decl_meta == TYPE_META_NIL) {
/* expect Nil */
bytecode_add_instruction(bc, OP_DUP, 0);
bytecode_add_instruction(bc, OP_TYPEOF, 0);
int ciNil = bytecode_add_constant(bc, make_string("Nil"));
bytecode_add_instruction(bc, OP_LOAD_CONST, ciNil);
bytecode_add_instruction(bc, OP_EQ, 0);
int j_to_error = bytecode_add_instruction(bc, OP_JUMP_IF_FALSE, 0);
int j_skip_err = bytecode_add_instruction(bc, OP_JUMP, 0);
bytecode_set_operand(bc, j_to_error, bc->instr_count);
{
int ciMsg = bytecode_add_constant(bc, make_string("TypeError: expected Nil"));
bytecode_add_instruction(bc, OP_LOAD_CONST, ciMsg);
bytecode_add_instruction(bc, OP_PRINT, 0);
bytecode_add_instruction(bc, OP_HALT, 0);
}
bytecode_set_operand(bc, j_skip_err, bc->instr_count);
} else {
/* integer widths: expect Number then clamp */
int abs_bits = decl_bits < 0 ? -decl_bits : decl_bits;
if (abs_bits > 0) {
/* typeof == Number */
bytecode_add_instruction(bc, OP_DUP, 0);
bytecode_add_instruction(bc, OP_TYPEOF, 0);
int ciNum = bytecode_add_constant(bc, make_string("Number"));
bytecode_add_instruction(bc, OP_LOAD_CONST, ciNum);
bytecode_add_instruction(bc, OP_EQ, 0);
int j_to_error = bytecode_add_instruction(bc, OP_JUMP_IF_FALSE, 0);
int j_skip_err = bytecode_add_instruction(bc, OP_JUMP, 0);
bytecode_set_operand(bc, j_to_error, bc->instr_count);
{
int ciMsg = bytecode_add_constant(bc, make_string("TypeError: expected Number"));
bytecode_add_instruction(bc, OP_LOAD_CONST, ciMsg);
bytecode_add_instruction(bc, OP_PRINT, 0);
bytecode_add_instruction(bc, OP_HALT, 0);
}
bytecode_set_operand(bc, j_skip_err, bc->instr_count);
bytecode_add_instruction(bc, (decl_bits < 0) ? OP_SCLAMP : OP_UCLAMP, abs_bits);
}
}
if (lidx >= 0) {
bytecode_add_instruction(bc, OP_STORE_LOCAL, lidx);
} else {
@ -1995,17 +2090,90 @@ static void parse_simple_statement(Bytecode *bc, const char *src, size_t len, si
if (local_pos < len && src[local_pos] == '=') {
local_pos++; /* '=' */
if (emit_expression(bc, src, len, &local_pos)) {
/* clamp to declared integer width if present */
int decl_bits = 0;
/* enforce declared type if present (0 = dynamic) */
int meta = 0;
if (lidx >= 0 && g_locals) {
decl_bits = g_locals->types[lidx];
meta = g_locals->types[lidx];
} else if (gi >= 0) {
decl_bits = G.types[gi];
meta = G.types[gi];
}
int abs_bits = decl_bits < 0 ? -decl_bits : decl_bits;
if (abs_bits > 0) {
bytecode_add_instruction(bc, (decl_bits < 0) ? OP_SCLAMP : OP_UCLAMP, abs_bits);
if (meta == TYPE_META_STRING) {
/* expect String */
bytecode_add_instruction(bc, OP_DUP, 0);
bytecode_add_instruction(bc, OP_TYPEOF, 0);
int ciStr = bytecode_add_constant(bc, make_string("String"));
bytecode_add_instruction(bc, OP_LOAD_CONST, ciStr);
bytecode_add_instruction(bc, OP_EQ, 0);
int j_to_error = bytecode_add_instruction(bc, OP_JUMP_IF_FALSE, 0);
int j_skip_err = bytecode_add_instruction(bc, OP_JUMP, 0);
bytecode_set_operand(bc, j_to_error, bc->instr_count);
{
int ciMsg = bytecode_add_constant(bc, make_string("TypeError: expected String"));
bytecode_add_instruction(bc, OP_LOAD_CONST, ciMsg);
bytecode_add_instruction(bc, OP_PRINT, 0);
bytecode_add_instruction(bc, OP_HALT, 0);
}
bytecode_set_operand(bc, j_skip_err, bc->instr_count);
} else if (meta == TYPE_META_BOOLEAN) {
/* expect Number then clamp to 1 bit (unsigned) */
bytecode_add_instruction(bc, OP_DUP, 0);
bytecode_add_instruction(bc, OP_TYPEOF, 0);
int ciNum = bytecode_add_constant(bc, make_string("Number"));
bytecode_add_instruction(bc, OP_LOAD_CONST, ciNum);
bytecode_add_instruction(bc, OP_EQ, 0);
int j_to_error = bytecode_add_instruction(bc, OP_JUMP_IF_FALSE, 0);
int j_skip_err = bytecode_add_instruction(bc, OP_JUMP, 0);
bytecode_set_operand(bc, j_to_error, bc->instr_count);
{
int ciMsg = bytecode_add_constant(bc, make_string("TypeError: expected Number for boolean"));
bytecode_add_instruction(bc, OP_LOAD_CONST, ciMsg);
bytecode_add_instruction(bc, OP_PRINT, 0);
bytecode_add_instruction(bc, OP_HALT, 0);
}
bytecode_set_operand(bc, j_skip_err, bc->instr_count);
bytecode_add_instruction(bc, OP_UCLAMP, 1);
} else if (meta == TYPE_META_NIL) {
/* expect Nil */
bytecode_add_instruction(bc, OP_DUP, 0);
bytecode_add_instruction(bc, OP_TYPEOF, 0);
int ciNil = bytecode_add_constant(bc, make_string("Nil"));
bytecode_add_instruction(bc, OP_LOAD_CONST, ciNil);
bytecode_add_instruction(bc, OP_EQ, 0);
int j_to_error = bytecode_add_instruction(bc, OP_JUMP_IF_FALSE, 0);
int j_skip_err = bytecode_add_instruction(bc, OP_JUMP, 0);
bytecode_set_operand(bc, j_to_error, bc->instr_count);
{
int ciMsg = bytecode_add_constant(bc, make_string("TypeError: expected Nil"));
bytecode_add_instruction(bc, OP_LOAD_CONST, ciMsg);
bytecode_add_instruction(bc, OP_PRINT, 0);
bytecode_add_instruction(bc, OP_HALT, 0);
}
bytecode_set_operand(bc, j_skip_err, bc->instr_count);
} else if (meta != 0) {
/* integer widths: expect Number then clamp to declared width */
int abs_bits = meta < 0 ? -meta : meta;
/* typeof == Number */
bytecode_add_instruction(bc, OP_DUP, 0);
bytecode_add_instruction(bc, OP_TYPEOF, 0);
int ciNum = bytecode_add_constant(bc, make_string("Number"));
bytecode_add_instruction(bc, OP_LOAD_CONST, ciNum);
bytecode_add_instruction(bc, OP_EQ, 0);
int j_to_error = bytecode_add_instruction(bc, OP_JUMP_IF_FALSE, 0);
int j_skip_err = bytecode_add_instruction(bc, OP_JUMP, 0);
bytecode_set_operand(bc, j_to_error, bc->instr_count);
{
int ciMsg = bytecode_add_constant(bc, make_string("TypeError: expected Number"));
bytecode_add_instruction(bc, OP_LOAD_CONST, ciMsg);
bytecode_add_instruction(bc, OP_PRINT, 0);
bytecode_add_instruction(bc, OP_HALT, 0);
}
bytecode_set_operand(bc, j_skip_err, bc->instr_count);
bytecode_add_instruction(bc, (meta < 0) ? OP_SCLAMP : OP_UCLAMP, abs_bits);
}
/* dynamic (meta==0): no enforcement */
if (lidx >= 0) {
bytecode_add_instruction(bc, OP_STORE_LOCAL, lidx);
} else {