update makefile and readme

first-interpreter/.gitignore

@@ -1,2 +1,3 @@
 _build
 interpreter
+interpreter.dSYM

first-interpreter/Makefile

@@ -4,33 +4,35 @@ endif
 
 CC = gcc
 CFLAGS = -Wall -Wextra -ggdb
+BUILD_DIR = _build
 
 .DEFAULT_TARGET = interpreter
 
-interpreter: src/main.c build/run.o
-	$(CC) $(CFLAGS) $< -o $@ build/run.o build/ast.o build/lex.o build/parse.o build/execute.o
+interpreter: src/main.c $(BUILD_DIR)/run.o
+	$(CC) $(CFLAGS) $< -o $@ $(BUILD_DIR)/run.o $(BUILD_DIR)/ast.o $(BUILD_DIR)/lex.o $(BUILD_DIR)/parse.o $(BUILD_DIR)/execute.o
 
-build/ast.o: src/ast.c src/ast.h
-	mkdir -p build/
+$(BUILD_DIR)/ast.o: src/ast.c src/ast.h
+	mkdir -p $(BUILD_DIR)/
 	$(CC) $(CFLAGS) -c $< -o $@
 
-build/lex.o: src/lex.c src/lex.h
-	mkdir -p build/
+$(BUILD_DIR)/lex.o: src/lex.c src/lex.h
+	mkdir -p $(BUILD_DIR)/
 	$(CC) $(CFLAGS) -c $< -o $@
 
-build/parse.o: src/parse.c src/parse.h build/ast.o build/lex.o
+$(BUILD_DIR)/parse.o: src/parse.c src/parse.h $(BUILD_DIR)/ast.o $(BUILD_DIR)/lex.o
 	$(CC) $(CFLAGS) -c $< -o $@
 
-build/execute.o: src/execute.c src/execute.h build/ast.o
+$(BUILD_DIR)/execute.o: src/execute.c src/execute.h $(BUILD_DIR)/ast.o
 	$(CC) $(CFLAGS) -c $< -o $@
 
-build/run.o: src/run.c src/run.h build/ast.o build/lex.o build/parse.o build/execute.o
+$(BUILD_DIR)/run.o: src/run.c src/run.h $(BUILD_DIR)/ast.o $(BUILD_DIR)/lex.o $(BUILD_DIR)/parse.o $(BUILD_DIR)/execute.o
 	$(CC) $(CFLAGS) -c $< -o $@
 
 .PHONY clean run:
 clean:
-	rm -rf build
+	rm -rf _build
 	rm -rf interpreter
+	rm -rf interpreter.dSYM
 
 run: interpreter
 	./interpreter program.code

first-interpreter/readme.md

@@ -0,0 +1,27 @@
+# My first interpreter
+
+Code for a very simple interpreter.
+
+Accompanying blogpost: https://alloca.space/blog/my-first-interpreter.html
+
+## Example Program
+
+```go
+sum = 0
+counter = 10
+
+while counter {
+    sum = add(sum, counter)
+    counter = add(counter, negate(1))
+}
+
+print(sum)
+```
+
+## Build and run
+
+Requires: gcc, make
+
+```sh
+make run
+```