diff --git a/example.script b/example.script
index af78fb1..ce2dd49 100644
--- a/example.script
+++ b/example.script
@@ -1,4 +1,4 @@
-x := 1
+/*x := 1
 y := 1
 
 i := 60
@@ -6,6 +6,12 @@ while i {
 	z := x + y
 	y = x
 	x = z
-	//print(z)
+	print(z)
 	i = i - 1
-}
+}*/
+
+f := 2.0
+
+a := int(pow(f, 2.0)) + 1
+
+print(a)
diff --git a/ir.c b/ir.c
index 735569c..0758307 100644
--- a/ir.c
+++ b/ir.c
@@ -10,9 +10,9 @@ const char *irinstr_str[IRInstrEnumSize] = {
 	[IRSub] = "sub",
 	[IRMul] = "mul",
 	[IRDiv] = "div",
-	[IRPrint] = "print",
 	[IRJmp] = "jmp",
 	[IRJnz] = "jnz",
+	[IRCallInternal] = "calli",
 };
 
 #define IRTOKS_INIT_CAP_LONG 4096
@@ -37,13 +37,8 @@ void irtoks_init_short(IRToks *v) {
 
 void irtoks_term(IRToks *v) {
 	for (size_t i = 0; i < v->len; i++) {
-		if (v->toks[i].instr == IRPrint) {
-			for (IRArgs *a = v->toks[i].Print.args; a != NULL;) {
-				IRArgs *next = a->next;
-				free(a);
-				a = next;
-			}
-		}
+		if (v->toks[i].instr == IRCallInternal)
+			free(v->toks[i].CallI.args);
 	}
 	free(v->toks);
 }
@@ -86,31 +81,25 @@ static void print_irparam(const IRParam *p) {
 	}
 }
 
-void print_ir(IRToks *v) {
+void print_ir(IRToks *v, const BuiltinFunc *builtin_funcs) {
 	for (size_t i = 0; i < v->len; i++) {
 		printf("%04zx ", i);
 		printf("%s", irinstr_str[v->toks[i].instr]);
 		switch (v->toks[i].instr) {
 			case IRSet:
 			case IRNeg:
-				printf(" %%%zu ", v->toks[i].Unary.addr);
+				printf(" %%%zx ", v->toks[i].Unary.addr);
 				print_irparam(&v->toks[i].Unary.val);
 				break;
 			case IRAdd:
 			case IRSub:
 			case IRDiv:
 			case IRMul:
-				printf(" %%%zu ", v->toks[i].Arith.addr);
+				printf(" %%%zx ", v->toks[i].Arith.addr);
 				print_irparam(&v->toks[i].Arith.lhs);
 				printf(" ");
 				print_irparam(&v->toks[i].Arith.rhs);
 				break;
-			case IRPrint:
-				for (IRArgs *a = v->toks[i].Print.args; a != NULL; a = a->next) {
-					printf(" ");
-					print_irparam(&a->param);
-				}
-				break;
 			case IRJmp:
 				printf(" %zx", v->toks[i].Jmp.iaddr);
 				break;
@@ -119,8 +108,16 @@ void print_ir(IRToks *v) {
 				print_irparam(&v->toks[i].CJmp.condition);
 				printf(" %zx", v->toks[i].CJmp.iaddr);
 				break;
-			default:
+			case IRCallInternal: {
+				const BuiltinFunc *f = &builtin_funcs[v->toks[i].CallI.fid];
+				printf(" %s %%%zx", f->name, v->toks[i].CallI.ret_addr);
+				for (size_t j = 0; j < f->n_args; j++) {
+					printf(" ");
+					print_irparam(&v->toks[i].CallI.args[j]);
+				}
 				break;
+			}
+			default: ASSERT_UNREACHED(); break;
 		}
 		printf(" ; %zu:%zu", v->toks[i].ln, v->toks[i].col);
 		printf("\n");
diff --git a/ir.h b/ir.h
index f74447c..1be102f 100644
--- a/ir.h
+++ b/ir.h
@@ -3,6 +3,14 @@
 
 #include "tok.h"
 
+typedef struct BuiltinFunc {
+	char *name;
+	bool side_effects : 1;
+	size_t n_args;
+	Value (*func)(Value *args);
+	size_t fid; /* function ID, assigned automatically */
+} BuiltinFunc;
+
 enum IRInstr {
 	IRSet,
 	IRNeg,
@@ -10,9 +18,9 @@ enum IRInstr {
 	IRSub,
 	IRMul,
 	IRDiv,
-	IRPrint,
 	IRJmp,
 	IRJnz,
+	IRCallInternal,
 	IRInstrEnumSize,
 };
 typedef enum IRInstr IRInstr;
@@ -66,6 +74,12 @@ typedef struct IRTok {
 			size_t iaddr;
 			IRParam condition;
 		} CJmp;
+
+		struct {
+			size_t ret_addr;
+			size_t fid;
+			IRParam *args;
+		} CallI;
 	};
 } IRTok;
 
@@ -80,6 +94,6 @@ void irtoks_term(IRToks *v);
 void irtoks_app(IRToks *v, IRTok t);
 void irtoks_app_irtoks(IRToks *v, IRToks *other);
 
-void print_ir(IRToks *v);
+void print_ir(IRToks *v, const BuiltinFunc *builtin_funcs);
 
 #endif /* IR_H */
diff --git a/main.c b/main.c
index 090ed17..e5a8669 100644
--- a/main.c
+++ b/main.c
@@ -32,6 +32,56 @@ static void die(const char *fmt, ...) {
 	exit(1);
 }
 
+static Value fn_print(Value *args) {
+	switch (args[0].type.kind) {
+		case TypeVoid:  printf("(void)\n");            break;
+		case TypeFloat: printf("%f\n", args[0].Float); break;
+		case TypeInt:   printf("%zd\n", args[0].Int);  break;
+		default:
+			ASSERT_UNREACHED();
+	}
+	return (Value){0};
+}
+
+static Value fn_int(Value *args) {
+	Value ret = {
+		.type.kind = TypeInt,
+		.Int = 0,
+	};
+	switch (args[0].type.kind) {
+		case TypeVoid: break;
+		case TypeFloat: ret.Int = (ssize_t)args[0].Float; break;
+		case TypeInt:   ret.Int = args[0].Int;            break;
+		default: ASSERT_UNREACHED();
+	}
+	return ret;
+}
+
+static Value fn_float(Value *args) {
+	Value ret = {
+		.type.kind = TypeFloat,
+		.Float = 0.0,
+	};
+	switch (args[0].type.kind) {
+		case TypeVoid: break;
+		case TypeFloat: ret.Float = args[0].Float;       break;
+		case TypeInt:   ret.Float = (double)args[0].Int; break;
+		default: ASSERT_UNREACHED();
+	}
+	return ret;
+}
+
+static Value fn_pow(Value *args) {
+	if (!(args[0].type.kind == TypeFloat && args[1].type.kind == TypeFloat)) {
+		set_err("pow() requires arguments of type float");
+		return (Value){0};
+	}
+	return (Value) {
+		.type.kind = TypeFloat,
+		.Float = pow(args[0].Float, args[1].Float),
+	};
+}
+
 int main(int argc, const char **argv) {
 	/* parse arguments */
 	size_t nargs = argc - 1;
@@ -88,7 +138,13 @@ int main(int argc, const char **argv) {
 	if (opt_emit_tokens)
 		print_toks(&tokens);
 	/* parse tokens into IR code */
-	IRToks ir = parse(&tokens);
+	BuiltinFunc funcs[] = {
+		{ .name = "print", .side_effects = true,  .n_args = 1, .func = fn_print, },
+		{ .name = "int",   .side_effects = false, .n_args = 1, .func = fn_int,   },
+		{ .name = "float", .side_effects = false, .n_args = 1, .func = fn_float, },
+		{ .name = "pow",   .side_effects = false, .n_args = 2, .func = fn_pow,   },
+	};
+	IRToks ir = parse(&tokens, funcs, sizeof(funcs) / sizeof(funcs[0]));
 	if (err) {
 		irtoks_term(&ir);
 		toklist_term(&tokens);
@@ -97,7 +153,7 @@ int main(int argc, const char **argv) {
 	}
 	toklist_term(&tokens);
 	if (opt_emit_ir)
-		print_ir(&ir);
+		print_ir(&ir, funcs);
 	/* run the IR */
 	/* TODO... */
 	irtoks_term(&ir);
diff --git a/parse.c b/parse.c
index 92d3f9c..3efd4f1 100644
--- a/parse.c
+++ b/parse.c
@@ -30,8 +30,8 @@ static size_t get_ident_addr(const Scope *sc, const char *name, const Tok *errpo
 static IRParam tok_to_irparam(Scope *sc, Tok *t);
 static Scope make_scope(Scope *parent, bool with_idents);
 static void term_scope(Scope *sc);
-static void expr(IRToks *out_ir, TokList *toks, Scope *parent_sc, TokListItem *t, ExprMode mode);
-static void stmt(IRToks *out_ir, TokList *toks, Scope *sc, TokListItem *t);
+static void expr(IRToks *out_ir, TokList *toks, Map *funcs, Scope *parent_sc, TokListItem *t, ExprMode mode);
+static void stmt(IRToks *out_ir, TokList *toks, Map *funcs, Scope *sc, TokListItem *t);
 
 static void mark_err(const Tok *t) {
 	err_ln = t->ln;
@@ -91,7 +91,7 @@ static void term_scope(Scope *sc) {
 		map_term(&sc->ident_addrs);
 }
 
-static void expr(IRToks *out_ir, TokList *toks, Scope *parent_sc, TokListItem *t, ExprMode mode) {
+static void expr(IRToks *out_ir, TokList *toks, Map *funcs, Scope *parent_sc, TokListItem *t, ExprMode mode) {
 	/* A simplified example of how the operator precedence parsing works:
 	 * ________________________________
 	 *  Where t points to (between l_op and r_op in each step)
@@ -145,6 +145,111 @@ static void expr(IRToks *out_ir, TokList *toks, Scope *parent_sc, TokListItem *t
 		if (mode.ignore_newln && t->next->tok.kind == TokOp && t->next->tok.Op == OpNewLn)
 			toklist_del(toks, t->next, t->next);
 
+		/* Collapse function call. */
+		if (t->tok.kind == TokIdent && t->tok.Ident.kind == IdentName && t->next->tok.kind == TokOp && t->next->tok.Op == OpLParen) {
+			BuiltinFunc func;
+			bool exists = map_get(funcs, t->tok.Ident.Name, &func);
+			if (!exists) {
+				mark_err(&t->tok);
+				set_err("Unrecognized function: %s()", t->tok.Ident.Name);
+				return;
+			}
+			TokListItem *func_ident = t;
+			t = t->next->next;
+			toklist_del(toks, t->prev, t->prev);
+
+			size_t n_args = 0;
+			TokListItem *first_arg = t;
+			TokListItem *last_arg = NULL;
+			
+			bool eval_func_in_place = !func.side_effects;
+			for (;;) {
+				n_args++;
+				TRY(expr(out_ir, toks, funcs, &sc, t, (ExprMode){ .kind = ExprModeJustCollapse, .ignore_newln = true }));
+				if (t->tok.kind == TokIdent)
+					eval_func_in_place = false;
+				if (t->next->tok.kind == TokOp) {
+					if (t->next->tok.Op == OpComma) {
+						toklist_del(toks, t->next, t->next);
+						t = t->next;
+						continue;
+					} else if (t->next->tok.Op == OpRParen) {
+						toklist_del(toks, t->next, t->next);
+						last_arg = t;
+						break;
+					}
+				}
+				mark_err(&t->next->tok);
+				set_err("Expected ',' or ')' after function argument");
+				return;
+			}
+
+			if (func.n_args != n_args) {
+				mark_err(&func_ident->tok);
+				const char *plural = func.n_args == 1 ? "" : "s";
+				set_err("Function %s() takes %zu argument%s but got %zu", func.name, func.n_args, plural, n_args);
+				return;
+			}
+
+			if (eval_func_in_place) {
+				Value *args = xmalloc(sizeof(Value) * n_args);
+				TokListItem *itm = first_arg;
+				for (size_t i = 0;; i++) {
+					args[i] = itm->tok.Val;
+					if (itm == last_arg)
+						break;
+					itm = itm->next;
+				}
+				func_ident->tok = (Tok) {
+					.kind = TokVal,
+					.Val = func.func(args),
+				};
+				free(args);
+			} else {
+				bool is_last_operation = func_ident == start && last_arg->next->tok.kind == TokOp && op_prec[last_arg->next->tok.Op] == PREC_DELIM;
+
+				IRParam *args = xmalloc(sizeof(IRParam) * n_args);
+				TokListItem *itm = first_arg;
+				for (size_t i = 0;; i++) {
+					TRY_ELSE(args[i] = tok_to_irparam(&sc, &itm->tok), free(args));
+					if (itm == last_arg)
+						break;
+					itm = itm->next;
+				}
+
+				size_t res_addr;
+				if (mode.kind == ExprModeStorageAddr && is_last_operation)
+					res_addr = mode.StorageAddr;
+				else
+					res_addr = sc.mem_addr++;
+				irtoks_app(out_ir, (IRTok){
+					.ln =  func_ident->tok.ln,
+					.col = func_ident->tok.col,
+					.instr = IRCallInternal,
+					.CallI = {
+						.ret_addr = res_addr,
+						.fid = func.fid,
+						.args = args,
+					},
+				});
+				if (mode.kind == ExprModeStorageAddr && is_last_operation) {
+					toklist_del(toks, func_ident, func_ident);
+					break;
+				} else {
+					func_ident->tok = (Tok) {
+						.kind = TokIdent,
+						.Ident = {
+							.kind = IdentAddr,
+							.Addr = res_addr,
+						},
+					};
+				}
+			}
+
+			t = func_ident;
+			toklist_del(toks, first_arg, last_arg);
+		}
+
 		/* Collapse negative factor. */
 		if (negate) {
 			bool is_last_operation = t->prev == start && t->next->tok.kind == TokOp && op_prec[t->next->tok.Op] == PREC_DELIM;
@@ -329,9 +434,9 @@ static void expr(IRToks *out_ir, TokList *toks, Scope *parent_sc, TokListItem *t
 	}
 }
 
-static void stmt(IRToks *out_ir, TokList *toks, Scope *sc, TokListItem *t) {
+static void stmt(IRToks *out_ir, TokList *toks, Map *funcs, Scope *sc, TokListItem *t) {
 	TokListItem *start = t;
-	if (t->tok.kind == TokIdent && t->tok.Ident.kind == IdentName) {
+	if (t->tok.kind == TokIdent && t->tok.Ident.kind == IdentName && (t->next->tok.kind == TokDeclare || t->next->tok.kind == TokAssign)) {
 		char *name = t->tok.Ident.Name;
 		t = t->next;
 		if (t->tok.kind == TokDeclare) {
@@ -343,13 +448,14 @@ static void stmt(IRToks *out_ir, TokList *toks, Scope *sc, TokListItem *t) {
 				set_err("'%s' already declared in this scope", name);
 				return;
 			}
-			TRY(expr(out_ir, toks, sc, t, (ExprMode){ .kind = ExprModeStorageAddr, .ignore_newln = false, .StorageAddr = addr }));
+			TRY(expr(out_ir, toks, funcs, sc, t, (ExprMode){ .kind = ExprModeStorageAddr, .ignore_newln = false, .StorageAddr = addr }));
 		} else if (t->tok.kind == TokAssign) {
 			t = t->next;
 			size_t addr;
 			TRY(addr = get_ident_addr(sc, name, &start->tok));
-			TRY(expr(out_ir, toks, sc, t, (ExprMode){ .kind = ExprModeStorageAddr, .ignore_newln = false, .StorageAddr = addr }));
-		}
+			TRY(expr(out_ir, toks, funcs, sc, t, (ExprMode){ .kind = ExprModeStorageAddr, .ignore_newln = false, .StorageAddr = addr }));
+		} else
+			ASSERT_UNREACHED();
 	} else if (t->tok.kind == TokOp && t->tok.Op == OpLCurl) {
 		Scope inner_sc = make_scope(sc, true);
 		for (;;) {
@@ -363,7 +469,7 @@ static void stmt(IRToks *out_ir, TokList *toks, Scope *sc, TokListItem *t) {
 				if (t->next->tok.Op == OpRCurl)
 					break;
 			}
-			TRY_ELSE(stmt(out_ir, toks, &inner_sc, t->next), term_scope(&inner_sc));
+			TRY_ELSE(stmt(out_ir, toks, funcs, &inner_sc, t->next), term_scope(&inner_sc));
 		}
 		term_scope(&inner_sc);
 		t = t->next;
@@ -392,7 +498,7 @@ static void stmt(IRToks *out_ir, TokList *toks, Scope *sc, TokListItem *t) {
 		/* parse condition */
 		IRToks cond_ir;
 		irtoks_init_short(&cond_ir);
-		TRY_ELSE(expr(&cond_ir, toks, sc, t, (ExprMode){ .kind = ExprModeJustCollapse, .ignore_newln = false }), irtoks_term(&cond_ir));
+		TRY_ELSE(expr(&cond_ir, toks, funcs, sc, t, (ExprMode){ .kind = ExprModeJustCollapse, .ignore_newln = true }), irtoks_term(&cond_ir));
 		IRParam cond_irparam;
 		TRY_ELSE(cond_irparam = tok_to_irparam(sc, &t->tok), irtoks_term(&cond_ir));
 		/* add conditional jump */
@@ -406,10 +512,8 @@ static void stmt(IRToks *out_ir, TokList *toks, Scope *sc, TokListItem *t) {
 			},
 		});
 
-		t = t->next;
-
 		/* parse loop body */
-		TRY_ELSE(stmt(out_ir, toks, sc, t), irtoks_term(&cond_ir));
+		TRY_ELSE(stmt(out_ir, toks, funcs, sc, t->next), irtoks_term(&cond_ir));
 
 		/* finally we know where the jmp from the beginning has to jump to */
 		out_ir->toks[jmp_instr_iaddr].Jmp.iaddr = out_ir->len;
@@ -417,19 +521,40 @@ static void stmt(IRToks *out_ir, TokList *toks, Scope *sc, TokListItem *t) {
 		/* append condition IR to program IR, then terminate condition IR stream */
 		irtoks_app_irtoks(out_ir, &cond_ir);
 		irtoks_term(&cond_ir);
+
+		t = t->next;
+	} else if (t->tok.kind == TokOp && t->tok.Op == OpNewLn) {
+	} else {
+		/* assume expression */
+		TRY(expr(out_ir, toks, funcs, sc, t, (ExprMode){ .kind = ExprModeJustCollapse, .ignore_newln = false }));
 	}
 	toklist_del(toks, start, t);
 }
 
-IRToks parse(TokList *toks) {
+IRToks parse(TokList *toks, BuiltinFunc *builtin_funcs, size_t n_builtin_funcs) {
+	Map funcs;
+	map_init(&funcs, sizeof(BuiltinFunc));
+	for (size_t i = 0; i < n_builtin_funcs; i++) {
+		builtin_funcs[i].fid = i;
+		bool replaced = map_insert(&funcs, builtin_funcs[i].name, &builtin_funcs[i]);
+		if (replaced) {
+			err_ln = 0; err_col = 0;
+			set_err("Builtin function %s() declared more than once", builtin_funcs[i].name);
+			map_term(&funcs);
+			return (IRToks){0};
+		}
+	}
+
 	IRToks ir;
 	irtoks_init_long(&ir);
 	Scope global_scope = make_scope(NULL, true);
 	for (;;) {
 		if (toks->begin->tok.kind == TokOp && toks->begin->tok.Op == OpEOF)
 			break;
-		TRY_RET_ELSE(stmt(&ir, toks, &global_scope, toks->begin), ir, term_scope(&global_scope));
+		TRY_RET_ELSE(stmt(&ir, toks, &funcs, &global_scope, toks->begin), ir,
+				{ term_scope(&global_scope); map_term(&funcs); });
 	}
 	term_scope(&global_scope);
+	map_term(&funcs);
 	return ir;
 }
diff --git a/parse.h b/parse.h
index 9707fb7..89d6704 100644
--- a/parse.h
+++ b/parse.h
@@ -5,6 +5,6 @@
 #include "tok.h"
 #include "util.h"
 
-IRToks parse(TokList *toks);
+IRToks parse(TokList *toks, BuiltinFunc *builtin_funcs, size_t n_builtin_funcs);
 
 #endif /* PARSE_H */