diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..cfb7081
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,26 @@
+CC=gcc
+YACC=yacc
+LEX=lex
+name=testl0
+lexf=$(name).l
+yaccf=$(name).y
+
+yacco=y.tab.h y.tab.c y.output
+lexo=lex.yy.c
+objs=$(yacco) $(lexo)
+
+$(name): $(filter %.c, $(objs)) node.o
+	$(CC) -o $@ $^
+
+$(yacco):
+	$(YACC) -dv $(yaccf)
+
+$(lexo):
+	$(LEX) $(lexf)
+
+node.o: node.c
+	gcc -c $^ -o $@
+
+.PHONY: clean
+clean:
+	rm -f $(objs) $(name)
diff --git a/node.c b/node.c
new file mode 100644
index 0000000..4575961
--- /dev/null
+++ b/node.c
@@ -0,0 +1,9 @@
+#include "node.h"
+#include <stdlib.h>
+
+node* node_float_new(double value) {
+    node_float* nf = malloc(sizeof(node_float));
+    nf->type = NODE_FLOAT;
+    nf->value = value;
+    return (node*)nf;
+}
diff --git a/node.h b/node.h
new file mode 100644
index 0000000..6a87b06
--- /dev/null
+++ b/node.h
@@ -0,0 +1,41 @@
+#ifndef TESTL0_H
+#define TESTL0_H
+
+enum node_type {
+  NODE_FLOAT
+};
+
+#define NODE_HEADER enum node_type type
+
+typedef struct {
+  NODE_HEADER;
+} node;
+
+typedef struct {
+  NODE_HEADER;
+  int len;
+  int max;
+  node** data;
+} node_nodes;
+
+typedef struct {
+  NODE_HEADER;
+  double value;
+} node_float;
+
+typedef struct node_string {
+  int len;
+  char buf[0];
+} *node_string;
+
+typedef struct {
+  NODE_HEADER;
+  node_string op;
+  node* lhs;
+  node* rhs;
+} node_op;
+
+
+node* node_float_new(double);
+
+#endif
diff --git a/node.o b/node.o
new file mode 100644
index 0000000..0e17fba
--- /dev/null
+++ b/node.o
Binary files differ
diff --git a/testl0.l b/testl0.l
new file mode 100644
index 0000000..32931ba
--- /dev/null
+++ b/testl0.l
@@ -0,0 +1,38 @@
+%{
+#include <stdio.h>
+#include "node.h"
+#include "y.tab.h"
+
+int
+yywrap(void)
+{
+  return 1;
+}
+%}
+
+%%
+"+" return ADD;
+"-" return SUB;
+"*" return MUL;
+"/" return DIV;
+"\n" return CR;
+
+"if" return IF;
+"(" return COND_BEGIN;
+")" return COND_END;
+"else" return ELSE;
+"endif" return ENDIF;
+
+[1-9][0-9]* {
+  double temp;
+  sscanf(yytext, "%lf", &temp);
+  yylval.double_value = temp;
+  return DOUBLE_LITERAL;
+}
+[0-9]*\.[0-9]* {
+  double temp;
+  sscanf(yytext, "%lf", &temp);
+  yylval.double_value = temp;
+  return DOUBLE_LITERAL;
+}
+%%
diff --git a/testl0.y b/testl0.y
new file mode 100644
index 0000000..e2d631e
--- /dev/null
+++ b/testl0.y
@@ -0,0 +1,83 @@
+%{
+#define YYDEBUG 1
+#include "node.h"
+#include <stdio.h>
+%}
+%union {
+  node* nd;
+  double double_value;
+}
+
+%type<nd> primary_expression
+%type<double_value> DOUBLE_LITERAL
+%type<double_value> expression term
+
+%token DOUBLE_LITERAL
+%token ADD SUB MUL DIV CR
+%token COND_BEGIN COND_END
+%token IF ELSE ENDIF
+
+%%
+line_list
+  : line
+  | line_list line
+  ;
+line
+  : expression CR
+  {
+    printf(">>%lf\n", $1);
+  }
+expression
+  : term
+  | expression ADD term
+  {
+    $$ = $1 + $3;
+  }
+  | expression SUB term
+  {
+    $$ = $1 - $3;
+  }
+  | IF COND_BEGIN expression COND_END expression ELSE expression ENDIF
+  {
+    $$ = ($3) ? ($5) : ($7);
+  }
+term
+  : primary_expression
+  {
+    $$ = ((node_float*)$1)->value;
+  }
+  | term MUL primary_expression
+  {
+    $$ = $1 * ((node_float*)$3)->value;
+  }
+  | term DIV primary_expression
+  {
+    $$ = $1 / ((node_float*)$3)->value;
+  }
+  ;
+primary_expression
+  : DOUBLE_LITERAL
+  {
+    $$ = node_float_new($1);
+  }
+  ;
+%%
+int
+yyerror(char const *str)
+{
+  extern char *yytext;
+  fprintf(stderr, "parser error near %s\n", yytext);
+  return 0;
+}
+
+int main(void)
+{
+  extern int yyparse(void);
+  extern FILE *yyin;
+
+  yyin = stdin;
+  if(yyparse()) {
+    fprintf(stderr, "Error! Error! Error!\n");
+    exit(1);
+  }
+}