diff --git a/.gitignore b/.gitignore
index 6a2f0f7..fc79a9e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 shell
 *.o
+libinterp.a
diff --git a/Makefile b/Makefile
index f81b589..1d66f11 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,9 @@
-CC = gcc -m32
+#CC = gcc -m32
+#AR = ar
+CC = arm-none-eabi-gcc -mcpu=cortex-m4 -mthumb -mfloat-abi=hard -mfpu=fpv4-sp-d16 -fsigned-char
+AR = arm-none-eabi-ar
 
-CFLAGS = -Wall -Wextra -Wno-strict-aliasing -I. -ggdb -fno-builtin
+CFLAGS = -Wall -Wextra -I. -fno-builtin -ggdb
 
 all:
 	$(CC) $(CFLAGS) -c shelpers.c
@@ -9,4 +12,6 @@ all:
 	$(CC) $(CFLAGS) -c stack.c
 	$(CC) $(CFLAGS) -c ops.c
 	$(CC) $(CFLAGS) -c variable.c
-	$(CC) $(CFLAGS) shell.c *.o -o shell
+	$(AR) r libinterp.a *.o
+	@rm -f *.o
+	#$(CC) $(CFLAGS) shell.c -o shell -L. -l interp
diff --git a/builtins.c b/builtins.c
index cda7a93..c77c8b9 100644
--- a/builtins.c
+++ b/builtins.c
@@ -1,7 +1,11 @@
 #include "builtins.h"
 #include "stack.h"
+#include "shelpers.h"
+
+#include <stdlib.h>
 
 extern char *str_func;
+extern char *str_undef;
 
 int ifunc_set(interpreter *it);
 int ifunc_label(interpreter *it);
@@ -11,6 +15,14 @@ int ifunc_do(interpreter *it);
 int ifunc_while(interpreter *it);
 int ifunc_ret(interpreter *it);
 
+const func_t indent_up[IUP_COUNT] = {
+	ifunc_if, ifunc_do, ifunc_label
+};
+
+const func_t indent_down[IDOWN_COUNT] = {
+	ifunc_end, ifunc_while
+};
+
 void iload_core(interpreter *interp)
 {
 	inew_cfunc(interp, "set", ifunc_set);
@@ -32,7 +44,9 @@ int ifunc_set(interpreter *it)
 
 	n->valtype = v->valtype;
 	n->value = v->value;
-	n->svalue = v->svalue;
+	if (n->svalue != 0 && n->svalue != str_func && n->svalue != str_undef)
+		free(n->svalue);
+	n->svalue = strclone(v->svalue);
 	return 0;
 }
 
@@ -46,25 +60,26 @@ int ifunc_label(interpreter *it)
 	n->valtype = FUNC;
 	n->value = it->lnidx;
 	n->svalue = str_func;
-	it->indent++;
+	iskip(it);
 	return 0;
 }
 
 int ifunc_if(interpreter *it)
 {
 	int v = igetarg_integer(it, 0);
-	if (v == 0) {
-		it->indent++;
-	} else {
-		void *tmp = ipop(it);
-		ipush(it, (void *)-1);
-		ipush(it, tmp);
-	}
+	if (v == 0)
+		iskip(it);
+	void *tmp = ipop(it);
+	ipush(it, (void *)-1);
+	ipush(it, tmp);
 	return 0;
 }
 
 int ifunc_end(interpreter *it)
 {
+	if (it->stidx == 0)
+		return 0;
+
 	uint32_t lnidx = (uint32_t)ipop(it) + 1;
 	if (lnidx != 0)
 		it->lnidx = lnidx;
@@ -83,8 +98,8 @@ int ifunc_while(interpreter *it)
 	ipop(it);
 	int nidx = (int)ipop(it);
 	if (c != 0) {
-		ipush(it, (void *)nidx);
-		it->lnidx = nidx;
+		//ipush(it, (void *)nidx);
+		it->lnidx = nidx - 1;
 	}
 	ipush(it, 0);
 	return 0;
diff --git a/builtins.h b/builtins.h
index 8739778..91c6e8c 100644
--- a/builtins.h
+++ b/builtins.h
@@ -3,6 +3,12 @@
 
 #include "parser.h"
 
+#define IUP_COUNT 3
+#define IDOWN_COUNT 2
+
 void iload_core(interpreter *it);
 
+const func_t indent_up[IUP_COUNT];
+const func_t indent_down[IDOWN_COUNT];
+
 #endif // BUILTINS_H_
diff --git a/parser.c b/parser.c
index ac739a0..b100123 100644
--- a/parser.c
+++ b/parser.c
@@ -7,6 +7,7 @@
 
 #include <ctype.h>
 #include <stdlib.h>
+#include <stdio.h>
 #include <string.h>
 
 #define MAX_VARS  48
@@ -24,9 +25,10 @@ void iinit(interpreter *interp)
 	interp->vnames = (char **)malloc(MAX_VARS * sizeof(char *));
 	interp->stack = (stack_t *)malloc(MAX_STACK * sizeof(stack_t));
 	interp->stidx = 0;
-	interp->lines = (char **)calloc(MAX_LINES, sizeof(char *));
+	interp->lines = (variable ***)malloc(MAX_LINES * sizeof(variable **));
 	interp->lnidx = 0;
 	interp->indent = 0;
+	interp->sindent = 0;
 
 	for (unsigned int i = 0; i < MAX_VARS; i++) {
 		interp->vars[i].used = 0;
@@ -38,6 +40,30 @@ void iinit(interpreter *interp)
 	iload_core(interp);
 }
 
+void iend(interpreter *it)
+{
+	for (unsigned int i = 0; i < MAX_VARS; i++) {
+		if (it->vars[i].used == 1) {
+			char *s = it->vars[i].svalue;
+			if (s != 0 && s != str_undef && s != str_func)
+				free(s);
+			free(it->vnames[i]);
+		}
+	}
+	for (unsigned int i = 0; i < MAX_LINES; i++)
+		free(it->lines[i]);
+	free(it->vars);
+	free(it->vnames);
+	free(it->stack);
+	free(it->lines);
+}
+
+void iskip(interpreter *it)
+{
+	if (!(it->sindent & SKIP))
+		it->sindent = it->indent | SKIP;
+}
+
 variable *interpreter_get_variable(interpreter *interp, const char *name)
 {
 	for (uint32_t i = 0; i < MAX_VARS; i++) {
@@ -66,7 +92,7 @@ char *interpreter_get_name(interpreter *interp, variable *v)
 	return str_undef;
 }
 
-void inew_string(interpreter *interp, const char *name, char *value)
+variable *inew_string(interpreter *interp, const char *name, char *value)
 {
 	variable *v = interpreter_get_variable(interp, name);
 	if (v != 0) {
@@ -74,9 +100,10 @@ void inew_string(interpreter *interp, const char *name, char *value)
 		INT(v) = 0;
 		v->svalue = strclone(value);
 	}
+	return v;
 }
 
-void inew_integer(interpreter *interp, const char *name, int32_t value)
+variable *inew_integer(interpreter *interp, const char *name, int32_t value)
 {
 	variable *v = interpreter_get_variable(interp, name);
 	if (v != 0) {
@@ -84,9 +111,10 @@ void inew_integer(interpreter *interp, const char *name, int32_t value)
 		INT(v) = value;
 		isetstr(v);
 	}
+	return v;
 }
 
-void inew_float(interpreter *interp, const char *name, float value)
+variable *inew_float(interpreter *interp, const char *name, float value)
 {
 	variable *v = interpreter_get_variable(interp, name);
 	if (v != 0) {
@@ -94,6 +122,7 @@ void inew_float(interpreter *interp, const char *name, float value)
 		FLOAT(v) = value;
 		fsetstr(v);
 	}
+	return v;
 }
 
 void inew_cfunc(interpreter *interp, const char *name, func_t func)
@@ -116,12 +145,8 @@ variable *make_var(interpreter *interp, const char *line, uint32_t *next)
 				if (!eot(line[end + 1]))
 					return 0;
 				// TODO string breakdown
-				variable *v = (variable *)malloc(sizeof(variable));
-				v->used = 0;
-				v->valtype = STRING;
-				v->svalue = strnclone(line + 1, end - 1);
 				*next = end + 1;
-				return v;
+				return vmake(0, STRING, strnclone(line + 1, end - 1));
 			}
 			end++;
 		}
@@ -131,7 +156,8 @@ variable *make_var(interpreter *interp, const char *line, uint32_t *next)
 		if (eot(line[end]))
 			return 0;
 		*next = end + 1;
-		return idoexpr(interp, line + 1);
+		return vmake(0, EXPR, strnclone(line + 1, end));
+		//return idoexpr(interp, line + 1);
 	} else if (isalpha(line[0])) { // variable/func
 		uint32_t end = 1;
 		for (; isalnum(line[end]); end++);
@@ -141,7 +167,9 @@ variable *make_var(interpreter *interp, const char *line, uint32_t *next)
 		strncpy(name, line, end);
 		name[end] = '\0';
 		*next = end;
-		return interpreter_get_variable(interp, name);
+		variable *v = interpreter_get_variable(interp, name);
+		free(name);
+		return v;
 	} else if (isdigit(line[0])) { // number
 		uint32_t end = 1;
 		uint8_t dec = 0;
@@ -157,17 +185,11 @@ variable *make_var(interpreter *interp, const char *line, uint32_t *next)
 				}
 			}
 		}
-		variable *v = (variable *)malloc(sizeof(variable));
-		v->used = 0;
+		variable *v;
 		if (dec) {
-			v->valtype = FLOAT;
-			FLOAT(v) = strtof(line, 0);
-			fsetstr(v);
-		} else {
-			v->valtype = INTEGER;
-			INT(v) = atoi(line);
-			isetstr(v);
-		}
+			v = vmakef(strtof(line, 0));
+		} else
+			v = vmake(0, INTEGER, (void *)atoi(line));
 		*next = end;
 		return v;
 	}
@@ -176,39 +198,34 @@ variable *make_var(interpreter *interp, const char *line, uint32_t *next)
 
 int idoline(interpreter *interp, const char *line)
 {
-	variable *ops[8];
-	uint32_t ooffset, offset, next;
+	uint32_t ooffset = 0, offset = 0, next;
+	int fret = 0;
 
 	if (line[0] == '\0')
 		return 0;
-
-	interp->lines[interp->lnidx] = strclone(line);
-loop:
-	ooffset = 0;
-	offset = 0;
 	skipblank(line, eol, &offset);
+	if (line[offset] == '#')
+		return 0;
 
-	if (line[offset] == '#') {
-		goto norun;
-	} else if (interp->indent > 0) {
-		if (!strcmp(line + offset, "end"))
-			interp->indent--;
-		goto norun;
-	}
+	interp->lines[interp->lnidx] = (variable **)calloc(8, sizeof(variable *));
+	variable **ops = interp->lines[interp->lnidx];
 
 	// step 1 - convert to tokens
 	while (!eol(line[offset])) {
 		if (offset > 0 && line[offset] == '>') {
 			offset++;
 			skipblank(line, eol, &offset);
-			interp->ret = make_var(interp, line + offset, &next);
+			variable *r = make_var(interp, line + offset, &next);
+			ops[ooffset] = (void *)-1;
+			ops[ooffset + 1] = r;
 			offset += next;
 			skipblank(line, eol, &offset);
 			continue;
 		}
 		ops[ooffset] = make_var(interp, line + offset, &next);
 		if (ops[ooffset] == 0) {
-			return -4;
+			fret = -4;
+			goto fail;
 		} else {
 			ooffset++;
 			offset += next;
@@ -217,14 +234,61 @@ loop:
 	}
 
 	// step 2 - execute
-	if (ooffset == 0)
-		return -1;
+	if (ooffset == 0) {
+		fret = -1;
+		goto fail;
+	}
+
+	if (ops[0]->valtype != FUNC) {
+		fret = -2;
+		goto fail;
+	}
 
-	if (ops[0]->valtype != FUNC)
-		return -2;
+	if (ops[0]->fromc && ops[0]->value == 0) {
+		fret = -3;
+		goto fail;
+	}
 
-	if (ops[0]->fromc && ops[0]->value == 0)
-		return -3;
+	if (ops[ooffset] != (void *)-1)
+		ops[ooffset] = 0;
+
+loop:
+	for (uint8_t i = 0; i < IUP_COUNT; i++) {
+		if (interp->lines[interp->lnidx][0]->value
+			== (uint32_t)indent_up[i]) {
+			interp->indent++;
+			goto cont;
+		}
+	}
+	for (uint8_t i = 0; i < IDOWN_COUNT; i++) {
+		if (interp->lines[interp->lnidx][0]->value
+			== (uint32_t)indent_down[i]) {
+			if (--interp->indent < 0) {
+				fret = -6;
+				goto fail;
+			}
+			if (interp->indent < (interp->sindent & ~(SKIP)))
+				interp->sindent &= ~(SKIP);
+			else
+				goto cont;
+			break;
+		}
+	}
+
+cont:
+	if (interp->indent > 0 && interp->sindent & SKIP)
+		goto norun;
+
+	ops = (variable **)malloc(8 * sizeof(variable *));
+	memcpy(ops, interp->lines[interp->lnidx], 8 * sizeof(variable *));
+	uint32_t oldLnidx = interp->lnidx;
+	
+	// eval expressions
+	ooffset = 1;
+	for (; ops[ooffset] != 0 && ops[ooffset] != (void *)-1; ooffset++) {
+		if (ops[ooffset]->valtype == EXPR)
+			ops[ooffset] = idoexpr(interp, ops[ooffset]->svalue);
+	}
 
 	if (ops[0]->fromc) {
 		for (uint32_t i = ooffset; --i > 0;)
@@ -237,7 +301,7 @@ loop:
 	} else {
 		char an[6];
 		for (uint32_t i = 1; i < ooffset; i++) {
-			snprintf(an, 6, "arg%d", i - 1);
+			snprintf(an, 6, "arg%d", (int)(i - 1));
 			switch (ops[i]->valtype) {
 			case STRING:
 				inew_string(interp, an, ops[i]->svalue);
@@ -255,26 +319,35 @@ loop:
 
 		ipush(interp, (void *)(interp->lnidx));
 		interp->lnidx = ops[0]->value;
+		interp->indent++;
 	}
 
+	if (ops[ooffset] == (void *)-1)
+		interp->ret = ops[ooffset + 1];
+
 	if ((int32_t)interp->stidx < 0) {
 		interp->stidx = 0;
 		return -5;
 	}
 
-	for (uint32_t i = 0; i < ooffset; i++) {
-		if (!ops[i]->used)
+	for (uint32_t i = 1; i < ooffset; i++) {
+		if (ops[i] != interp->lines[oldLnidx][i]) {
+			free(ops[i]->svalue);
 			free(ops[i]);
+		}
 	}
-
+	free(ops);
 norun:
 	interp->lnidx++;
-	if (interp->lines[interp->lnidx] != 0) {
-		line = interp->lines[interp->lnidx];
+	if (interp->lines[interp->lnidx] != 0)
 		goto loop;
-	}
 
 	return 0;
+
+fail:
+	free(interp->lines[interp->lnidx]);
+	interp->lines[interp->lnidx] = 0;
+	return fret;
 }
 
 variable *idoexpr(interpreter *interp, const char *line)
@@ -359,10 +432,16 @@ variable *idoexpr(interpreter *interp, const char *line)
 	}
 
 	for (uint32_t i = 0; i < ooffset; i += 2) {
-		if (!((variable *)ops[i])->used)
+		if (!((variable *)ops[i])->used) {
+			char *s = ((variable *)ops[i])->svalue;
+			if (s != 0 && s != str_undef)
+				free(s);
 			free(ops[i]);
+		}
 	}
-
+	
+	result->used = 0;
+	result->svalue = 0;
 	if (result->valtype == INTEGER)
 		isetstr(result);
 	else
diff --git a/parser.h b/parser.h
index 4e4699e..92a8eb3 100644
--- a/parser.h
+++ b/parser.h
@@ -10,19 +10,25 @@ typedef struct {
 	char **vnames;
 	stack_t *stack;
 	uint32_t stidx;
-	char **lines;
+	variable ***lines;
 	uint32_t lnidx;
-	uint8_t indent;
+	int8_t indent;
+	uint8_t sindent;
 	variable *ret;
 } interpreter;
 
+#define SKIP (1 << 7)
+
 typedef int (*func_t)(interpreter *);
 
 void iinit(interpreter *);
+void iend(interpreter *it);
+
+void iskip(interpreter *it);
 
-void inew_string(interpreter *, const char *, char *);
-void inew_integer(interpreter *, const char *, int32_t);
-void inew_float(interpreter *, const char *, float);
+variable *inew_string(interpreter *, const char *, char *);
+variable *inew_integer(interpreter *, const char *, int32_t);
+variable *inew_float(interpreter *, const char *, float);
 void inew_cfunc(interpreter *, const char *, func_t);
 
 int idoline(interpreter *, const char *);
diff --git a/script b/script
index 3b807a2..dac7da5 100644
--- a/script
+++ b/script
@@ -1,17 +1,18 @@
-func inc
-	set arg0 (arg0 + 1)
-	ret arg0
+func divisible
+	if (arg1 == 0)
+		ret 0
+	end
+	ret (arg0 % arg1)
 end
 
 set a 0
+set b 4
 do
-	inc a > a
-	if ((a % 9) == 0)
-		put a
+	set a (a + 1)
+	divisible a b > i
+	if (i == 0)
+		print a
 	end
 while (a < 100)
 
-if (a == 100)
-	put "All good!"
-end
-
+print "All done!"
diff --git a/shell.c b/shell.c
index 0c0c4df..c63b1bc 100644
--- a/shell.c
+++ b/shell.c
@@ -59,7 +59,7 @@ int main(int argc, char **argv)
 	}
 
 	iinit(&interp);
-	inew_cfunc(&interp, "put", s_put);
+	inew_cfunc(&interp, "print", s_put);
 	inew_cfunc(&interp, "tp", s_type);
 	inew_cfunc(&interp, "q", quit);
 
@@ -75,5 +75,6 @@ int main(int argc, char **argv)
 	}
 
 	fclose(fp);
+	iend(&interp);
 	return 0;
 }
diff --git a/shelpers.c b/shelpers.c
index 0d2da24..fbde4ab 100644
--- a/shelpers.c
+++ b/shelpers.c
@@ -14,6 +14,7 @@ char *strnclone(const char *s, uint32_t n)
 {
 	char *clone = (char *)malloc(n + 1);
 	strncpy(clone, s, n);
+	clone[n] = '\0';
 	return clone;
 }
 
diff --git a/variable.c b/variable.c
index 727ca0c..620a4b6 100644
--- a/variable.c
+++ b/variable.c
@@ -5,6 +5,47 @@
 #include <stdlib.h>
 
 extern char *str_undef;
+extern char *str_func;
+
+variable *vmake(uint8_t fromc, uint8_t valtype, void *value)
+{
+	variable *v = (variable *)malloc(sizeof(variable));
+	v->used = 0;
+	v->fromc = fromc;
+	v->valtype = valtype;
+	v->value = 0;
+	v->svalue = 0;
+	switch (valtype) {
+	case STRING:
+		v->value = 0;
+		v->svalue = value;
+		break;
+	case INTEGER:
+		INT(v) = (int32_t)value;
+		isetstr(v);
+		break;
+	case FUNC:
+		v->value = (uint32_t)value;
+		v->svalue = str_func;
+		break;
+	case EXPR:
+		v->value = 0;
+		v->svalue = value;
+		break;
+	}
+	return v;
+}
+
+variable *vmakef(float value)
+{
+	variable *v = (variable *)malloc(sizeof(variable));
+	v->used = 0;
+	v->fromc = 0;
+	v->valtype = FLOAT;
+	FLOAT(v) = value;
+	fsetstr(v);
+	return v;
+}
 
 void fsetstr(variable *f)
 {
@@ -17,7 +58,7 @@ void isetstr(variable *i)
 {
 	if (i->svalue == 0 || i->svalue == str_undef)
 		i->svalue = (char *)malloc(12);
-	snprintf(i->svalue, 12, "%d", INT(i));
+	snprintf(i->svalue, 12, "%d", (int)INT(i));
 }
 
 variable *itostring(variable *v)
diff --git a/variable.h b/variable.h
index 82c6b25..e5aa20c 100644
--- a/variable.h
+++ b/variable.h
@@ -9,7 +9,7 @@
 typedef struct {
 	uint8_t used :1;
 	uint8_t fromc :1;
-	uint8_t valtype :2;
+	uint8_t valtype :4;
 	uint32_t value;
 	char *svalue;
 } variable;
@@ -18,9 +18,13 @@ enum valtype {
 	STRING = 0,
 	INTEGER,
 	FLOAT,
-	FUNC
+	FUNC,
+	EXPR
 };
 
+variable *vmake(uint8_t fromc, uint8_t valtype, void *value);
+variable *vmakef(float value);
+
 void isetstr(variable *i);
 void fsetstr(variable *f);