diff --git a/byterun/src/sm_parser.cpp b/byterun/src/sm_parser.cpp
index f173398cb..0e7d86157 100644
--- a/byterun/src/sm_parser.cpp
+++ b/byterun/src/sm_parser.cpp
@@ -2,6 +2,8 @@
 
 #include <charconv>
 #include <iostream>
+#include <sstream>
+#include <unordered_map>
 
 std::vector<SMInstr> parse_sm(std::istream &in) {
   std::vector<SMInstr> result;
@@ -33,4 +35,126 @@ parse(std::string::iterator begin, std::string::iterator end) {
   // TODO
 }
 
-std::optional<SMInstr> parse_sm(const std::string &line) {}
+std::string substr_to(const std::string &line, size_t &pos, char to) {
+  auto offset = line.find(pos, to);
+
+  if (offset == std::string::npos) {
+    return "";
+  };
+
+  std::string result = line.substr(pos, offset);
+  pos += offset + 1;
+
+  return result;
+}
+
+struct SMInstrBuilder {
+public:
+  SMInstrBuilder(SMInstr instr) : instr(instr), args_pushed(0) {}
+
+  SMInstr build() {
+    // TODO: check for all arps
+    return instr;
+  }
+
+  // TODO
+  void push_arg(std::string &&value) {}
+  void push_arg(bool value) {}
+  void push_arg(int value) {}
+  void push_arg(ValT value) {}
+  void push_arg(Patt value) {}
+
+private:
+  SMInstr instr;
+  size_t args_pushed = 0;
+}
+
+std::optional<SMInstr>
+parse_sm(const std::string &line) {
+  std::unordered_map<std::string, SMInstr> to_instr = {
+      {"BINOP", SMInstr{SMInstr::BINOP{}}},
+      {"CONST", SMInstr{SMInstr::CONST{}}},
+      {"STRING", SMInstr{SMInstr::STRING{}}},
+      {"SEXP", SMInstr{SMInstr::SEXP{}}},
+      {"LD", SMInstr{SMInstr::LD{ValT::Global{}}}},   // NOTE: as default
+      {"LDA", SMInstr{SMInstr::LDA{ValT::Global{}}}}, // NOTE: as default
+      {"ST", SMInstr{SMInstr::ST{ValT::Global{}}}},   // NOTE: as default
+      {"STI", SMInstr{SMInstr::STI{}}},
+      {"STA", SMInstr{SMInstr::STA{}}},
+      {"ELEM", SMInstr{SMInstr::ELEM{}}},
+      {"LABEL", SMInstr{SMInstr::LABEL{}}},
+      {"FLABEL", SMInstr{SMInstr::FLABEL{}}},
+      {"SLABEL", SMInstr{SMInstr::SLABEL{}}},
+      {"JMP", SMInstr{SMInstr::JMP{}}},
+      {"CJMP", SMInstr{SMInstr::CJMP{}}},
+      {"BEGIN", SMInstr{SMInstr::BEGIN{}}},
+      {"END", SMInstr{SMInstr::END{}}},
+      {"CLOSURE", SMInstr{SMInstr::CLOSURE{}}},
+      {"CALLC", SMInstr{SMInstr::CALLC{}}},
+      {"CALL", SMInstr{SMInstr::CALL{}}},
+      {"RET", SMInstr{SMInstr::RET{}}},
+      {"DROP", SMInstr{SMInstr::DROP{}}},
+      {"DUP", SMInstr{SMInstr::DUP{}}},
+      {"SWAP", SMInstr{SMInstr::SWAP{}}},
+      {"TAG", SMInstr{SMInstr::TAG{}}},
+      {"ARRAY", SMInstr{SMInstr::ARRAY{}}},
+      {"PATT", SMInstr{SMInstr::PATT{}}},
+      {"FAIL", SMInstr{SMInstr::FAIL{}}},
+      {"EXTERN", SMInstr{SMInstr::EXTERN{}}},
+      {"PUBLIC", SMInstr{SMInstr::PUBLIC{}}},
+      {"IMPORT", SMInstr{SMInstr::IMPORT{}}},
+      {"LINE", SMInstr{SMInstr::LINE{}}},
+  };
+
+  char ch; // NOTE: for helpers
+
+  size_t pos = 0;
+  std::string cmd = substr_to(line, pos, ' ');
+
+  auto instr_it = to_instr.find(cmd);
+  if (instr_it == to_instr.end()) {
+    return std::nullopt;
+  }
+  SMInstrBuilder instr{instr_it->second};
+
+  // no args case
+  if (pos == line.size()) {
+    return instr.build();
+  }
+
+  if (std::string space = substr_to(line, pos, '('); space != " ") {
+    return std::nullopt;
+  }
+
+  bool was_last_arg = false;
+  while (!was_last_arg) {
+    std::string arg = substr_to(line, pos, '(');
+    ++pos;
+
+    if (arg.empty()) {
+      arg = line.substr(pos);
+      arg.pop_back(); // ')'
+      was_last_arg = true;
+    }
+
+    if (arg.front() == '"') {
+      instr.push_arg(arg.substr(1, arg.size() - 2));
+    } else if (arg == "true") {
+      instr.push_arg(true);
+    } else if (arg == "false") {
+      instr.push_arg(false);
+    } else if () { // TODO: Local, Global, Arg
+    } else if () { // TODO: BEGIN vectors, etc
+    } else if () { // TODO: PATT patterns
+    } else if () { // TODO: CLUSURE vector
+    } else if (int n = 0; std::from_chars(line.data() + pos,
+                                          line.data() + pos + line.size(), n)
+                              .ec == std::errc{}) {
+      instr.push_arg(n);
+    } else {
+      return std::nullopt;
+    }
+  }
+
+  return instr.build();
+}