diff --git a/ast.c b/ast.c
index f94ddb7..f8bd3cd 100644
--- a/ast.c
+++ b/ast.c
@@ -2,37 +2,97 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <string.h>
 
 #include "ast.h"
+#include "parse.h"
 
-int ast_parse(const char* source, uint32_t len, ast *result) {
+ast ast_parse(const char* source, const uint32_t len, int* err)
+{
     uint32_t estimated_token_count = len / 8;
 
-    tokenizer_tag* tokens_tag = calloc(estimated_token_count, sizeof(tokenizer_tag));
-    if (tokens_tag == NULL) {
-        perror("calloc");
-        return 1;
-    }
-    ast_index* tokens_start = calloc(estimated_token_count, sizeof(ast_index));
-    if (tokens_start == NULL) {
-        free(tokens_tag);
-        perror("calloc");
-        return 1;
-    }
+    tokenizer_tag* token_tags = NULL;
+    ast_index* token_starts = NULL;
+    ast_node_tag* nodes_tags = NULL;
+    ast_token_index* main_tokens = NULL;
+    ast_data* nodes_datas = NULL;
+    ast_node_index* extra_data_arr = NULL;
+    ast_node_index* scratch_arr = NULL;
 
-    tokenizer tokenizer = tokenizer_init(source, len);
-    for (uint32_t i = 0; i <= estimated_token_count; i++) {
-        if (i == estimated_token_count) {
+    if (!(token_tags = calloc(estimated_token_count, sizeof(tokenizer_tag))))
+        goto err;
+
+    if (!(token_starts = calloc(estimated_token_count, sizeof(ast_index))))
+        goto err;
+
+    tokenizer tok = tokenizer_init(source, len);
+    uint32_t tokens_len = 0;
+    for (; tokens_len <= estimated_token_count; tokens_len++) {
+        if (tokens_len == estimated_token_count) {
             fprintf(stderr, "too many tokens, bump estimated_token_count\n");
-            return 1;
+            goto err;
         }
-        tokenizer_token token = tokenizer_next(&tokenizer);
-        tokens_tag[i] = token.tag;
-        tokens_start[i] = token.loc.start;
+        tokenizer_token token = tokenizer_next(&tok);
+        token_tags[tokens_len] = token.tag;
+        token_starts[tokens_len] = token.loc.start;
     }
 
-    /* TODO parser */
+    uint32_t estimated_node_count = (tokens_len + 2) / 2;
 
-    return 0;
+    if (!(nodes_tags = calloc(estimated_node_count, sizeof(ast_node_tag))))
+        goto err;
+
+    if (!(main_tokens = calloc(estimated_node_count, sizeof(ast_token_index))))
+        goto err;
+
+    if (!(nodes_datas = calloc(estimated_node_count, sizeof(ast_data))))
+        goto err;
+
+    if (!(extra_data_arr = calloc(16, sizeof(ast_token_index))))
+        goto err;
+
+    if (!(scratch_arr = calloc(16, sizeof(ast_token_index))))
+        goto err;
+
+    parser p = (parser) {
+        .source = source,
+        .source_len = len,
+        .token_tags = token_tags,
+        .token_starts = token_starts,
+        .tokens_len = tokens_len,
+        .tok_i = 0,
+        .nodes = (ast_node_list) {
+            .len = 0,
+            .cap = estimated_node_count,
+            .tags = nodes_tags,
+            .main_tokens = main_tokens,
+            .datas = nodes_datas,
+        },
+        .extra_data = (parser_node_index_slice) { .len = 0, .cap = 16, .arr = extra_data_arr },
+        .scratch = (parser_node_index_slice) { .len = 0, .cap = 16, .arr = scratch_arr },
+    };
+
+    free(scratch_arr);
+
+    // TODO work
+
+    return (ast) {
+        .source = source,
+        .tokens.tags = token_tags,
+        .tokens.starts = token_starts,
+        .nodes = p.nodes,
+        .extra_data = p.extra_data.arr,
+        .extra_data_len = p.extra_data.len,
+    };
+
+err:
+    free(token_tags);
+    free(token_starts);
+    free(nodes_tags);
+    free(main_tokens);
+    free(nodes_datas);
+    free(extra_data_arr);
+    free(scratch_arr);
+
+    *err = 1;
+    return (ast) {};
 }
diff --git a/ast.h b/ast.h
index 443e5f8..728d274 100644
--- a/ast.h
+++ b/ast.h
@@ -486,26 +486,33 @@ typedef uint32_t ast_node_index;
 typedef uint32_t ast_index;
 
 typedef struct {
-    ast_node_tag tag;
-    ast_token_index main_token;
-    struct {
-        ast_index lhs, rhs;
-    } data;
-} ast_node;
+    ast_index lhs, rhs;
+} ast_data;
+
+typedef struct {
+    uint32_t len;
+    uint32_t cap;
+    ast_node_tag* tags;
+    ast_token_index* main_tokens;
+    ast_data* datas;
+} ast_node_list;
 
 typedef struct {
     const char* source;
-    uint32_t source_len;
+    const uint32_t source_len;
 
-    tokenizer_tag* tokens_tag;
-    ast_index* tokens_start;
-    uint32_t tokens_len;
+    struct {
+        uint32_t len;
+        tokenizer_tag* tags;
+        ast_index* starts;
+    } tokens;
+
+    ast_node_list nodes;
 
-    ast_node* nodes;
-    uint32_t nodes_len;
     ast_node_index* extra_data;
+    uint32_t extra_data_len;
 } ast;
 
-int ast_parse(const char* source, uint32_t len, ast *result);
+ast ast_parse(const char* source, uint32_t len, int* err);
 
 #endif
diff --git a/build.zig b/build.zig
index 8e36628..e1245b3 100644
--- a/build.zig
+++ b/build.zig
@@ -1,5 +1,8 @@
 const std = @import("std");
 
+const c_lib = &[_][]const u8{ "tokenizer.c", "ast.c", "zig1.c" };
+const all_c_files = c_lib ++ &[_][]const u8{"main.c"};
+
 pub fn build(b: *std.Build) void {
     const target = b.standardTargetOptions(.{});
     const optimize = b.standardOptimizeOption(.{});
@@ -9,8 +12,8 @@ pub fn build(b: *std.Build) void {
         .optimize = optimize,
         .target = target,
     });
-    lib.addCSourceFile(.{
-        .file = b.path("tokenizer.c"),
+    lib.addCSourceFiles(.{
+        .files = c_lib,
         .flags = &[_][]const u8{
             "-std=c11",
             "-Wall",
@@ -35,13 +38,44 @@ pub fn build(b: *std.Build) void {
     lib.linkLibC();
 
     const test_step = b.step("test", "Run unit tests");
-
     const test_exe = b.addTest(.{
         .root_source_file = b.path("test_all.zig"),
         .optimize = optimize,
     });
     test_exe.linkLibrary(lib);
     test_exe.addIncludePath(b.path("."));
-
     test_step.dependOn(&b.addRunArtifact(test_exe).step);
+
+    const lint_step = b.step("lint", "Run linters");
+    const clang_format = b.addSystemCommand(&.{"clang-format"});
+    clang_format.addArgs(&.{ "--style=webkit", "-i" });
+    for (all_c_files) |cfile| clang_format.addFileArg(b.path(cfile));
+    lint_step.dependOn(&clang_format.step);
+
+    const clang_analyze = b.addSystemCommand(&.{"clang"});
+    clang_analyze.addArgs(&.{
+        "--analyze",
+        "--analyzer-output",
+        "text",
+        "-Wno-unused-command-line-argument",
+        "-Werror",
+    });
+    for (all_c_files) |cfile| clang_analyze.addFileArg(b.path(cfile));
+    lint_step.dependOn(&clang_analyze.step);
+
+    const gcc_analyze = b.addSystemCommand(&.{"gcc"});
+    gcc_analyze.addArgs(&.{ "--analyzer", "-Werror", "-o", "/dev/null" });
+    for (all_c_files) |cfile| gcc_analyze.addFileArg(b.path(cfile));
+    lint_step.dependOn(&gcc_analyze.step);
+
+    const cppcheck = b.addSystemCommand(&.{"cppcheck"});
+    cppcheck.addArgs(&.{
+        "--enable=all",
+        "--suppress=missingIncludeSystem",
+        "--suppress=checkersReport",
+        "--quiet",
+        "--suppress=unusedFunction", // TODO remove after plumbing is done
+    });
+    for (all_c_files) |cfile| cppcheck.addFileArg(b.path(cfile));
+    lint_step.dependOn(&cppcheck.step);
 }
diff --git a/main.c b/main.c
index 7509364..5c933f5 100644
--- a/main.c
+++ b/main.c
@@ -5,7 +5,7 @@
 int zig1_run(char* program, char** msg);
 int zig1_run_file(char* fname, char** msg);
 
-static void usage(char* argv0)
+static void usage(const char* argv0)
 {
     fprintf(stderr, "Usage: %s program.zig\n", argv0);
 }
diff --git a/parse.h b/parse.h
new file mode 100644
index 0000000..765fa98
--- /dev/null
+++ b/parse.h
@@ -0,0 +1,30 @@
+#ifndef _ZIG1_PARSE_H__
+#define _ZIG1_PARSE_H__
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "ast.h"
+
+typedef struct {
+    uint32_t len;
+    uint32_t cap;
+    ast_node_index* arr;
+} parser_node_index_slice;
+
+typedef struct {
+    const char* source;
+    const uint32_t source_len;
+
+    tokenizer_tag* token_tags;
+    ast_index* token_starts;
+    uint32_t tokens_len;
+
+    ast_token_index tok_i;
+
+    ast_node_list nodes;
+    parser_node_index_slice extra_data;
+    parser_node_index_slice scratch;
+} parser;
+
+#endif
diff --git a/tokenizer.c b/tokenizer.c
index 9e1bb41..a2df204 100644
--- a/tokenizer.c
+++ b/tokenizer.c
@@ -63,7 +63,7 @@ const keyword_map keywords[] = {
 };
 
 // TODO binary search
-static tokenizer_tag get_keyword(const char* bytes, uint32_t len)
+static tokenizer_tag get_keyword(const char* bytes, const uint32_t len)
 {
     for (unsigned long i = 0; i < sizeof(keywords) / sizeof(keyword_map); i++) {
         size_t klen = strlen(keywords[i].keyword);
@@ -78,12 +78,11 @@ static tokenizer_tag get_keyword(const char* bytes, uint32_t len)
         } else if (cmp < 0) {
             return TOKENIZER_TAG_INVALID;
         }
-        continue;
     }
     return TOKENIZER_TAG_INVALID;
 }
 
-tokenizer tokenizer_init(const char* buffer, uint32_t len)
+tokenizer tokenizer_init(const char* buffer, const uint32_t len)
 {
     return (tokenizer) {
         .buffer = buffer,
diff --git a/tokenizer.h b/tokenizer.h
index 206ab50..d1dc242 100644
--- a/tokenizer.h
+++ b/tokenizer.h
@@ -186,7 +186,7 @@ typedef struct {
 
 typedef struct {
     const char* buffer;
-    uint32_t buffer_len;
+    const uint32_t buffer_len;
     uint32_t index;
 } tokenizer;
 
diff --git a/zig1.c b/zig1.c
index 614ba16..93ba67f 100644
--- a/zig1.c
+++ b/zig1.c
@@ -6,11 +6,16 @@
 // - code = 0: program successfully terminated.
 // - code = 1: panicked, panic message in msg. Caller should free msg.
 // - code = 2: interpreter error, error in msg. Caller should free msg.
-int zig1_run(char* program, char** msg) { return 0; }
+int zig1_run(const char* program, char** msg)
+{
+    (void)program;
+    (void)msg;
+    return 0;
+}
 
 // API: run and:
 // code = 3: abnormal error, expect something in stderr.
-int zig1_run_file(char* fname, char** msg)
+int zig1_run_file(const char* fname, char** msg)
 {
     FILE* f = fopen(fname, "r");
     if (f == NULL) {
@@ -18,12 +23,13 @@ int zig1_run_file(char* fname, char** msg)
         return 3;
     }
     fseek(f, 0, SEEK_END);
-    long fsize = ftell(f);
-    if (fsize == -1) {
+    long fsizel = ftell(f);
+    if (fsizel == -1) {
         perror("ftell");
         fclose(f);
         return 3;
     }
+    unsigned long fsize = (unsigned long)fsizel;
     fseek(f, 0, SEEK_SET);
 
     char* program = malloc(fsize + 1);