supporting pause&resume

Author: sdingcn

.gitignore

@@ -1,3 +1,5 @@
+/bin/clo
+/bin/clo.dSYM/
 /bin/clocalc
 /bin/clocalc.dSYM/
 /src/.vscode/

README.md

@@ -1,38 +1,42 @@
-# clocalc
+# clo
 
-![](https://github.com/sdingcn/clocalc/actions/workflows/run_test.yml/badge.svg)
+![](https://github.com/sdingcn/clo/actions/workflows/run_test.yml/badge.svg)
 
-**Clo**sure **calc**ulus is an interpreted functional programming language.
-See [test/](test/) for code examples (`*.clo`).
+**Clo** is an interpreted programming language.
 
-## syntax
+The distinguished feature of this language is the ability to save
+the current program state as a string.
+The built-in function `.forkstate` returns
+a string encoding the entire program state,
+and when the state is resumed using `.eval` it starts
+right after the `.forkstate` call but with a return value of Void type.
+```
+{
+  (.putstr "0\n")
+  (.putstr "1\n")
+  letrec (state (.forkstate)) {
+    (.putstr "2\n")
+    if (.= (.type state) 0)  # if it is a void value
+       (.putstr "3\n")
+       (.eval state)
+  }
+}
+```
 
+The other features of this language is just a normal
+dynamically typed function programming language.
 ```
-<comment>   := #[^\n]*\n
-<integer>   := [+-]?[0-9]+  // C++ int
-<string>    := "([^"] | \")*"  // see interpreter source for the supported alphabet
-<variable>  := [a-zA-Z_][a-zA-Z0-9_]*
-<intrinsic> := .void  // generates a Void object
-             | .+ | .- | .* | ./ | .% | .< | .<= | .> | .>= | .= | ./=
-             | .and | .or | .not  // no short-circuit; use "if" for short-circuit
-             | .s+ | .s< | .s<= | .s> | .s>= | .s= | .s/= | .s|| | .s[] | .quote | .unquote
-             | .s->i | .i->s
-             | .type  // 0 for Void, 1 for Int, 2 for String, 3 for Closure
-             | .eval
-             | .getchar | .getint | .putstr | .flush  // IO
-<vepair>    := <variable> <expr>
-<expr>      := <integer>
-             | <string>
-             | <variable>
-             | lambda ( <variable>* ) <expr>
-             | letrec ( <vepair>* ) <expr>
-             | if <expr> <expr> <expr>
-             | { <expr>+ }  // sequenced evaluation
-             | ( <intrinsic> <expr>* )
-             | ( <expr> <expr>* )
-             | @ <variable> <expr>  // accesses a closure's environment variable
+letrec (
+    sum lambda (n acc)
+        if (.< n 1)
+        acc
+        (sum (.- n 1) (.+ acc n))
+)
+(sum (.getint) 0)
 ```
 
+See [test/](test/) for more code examples (`*.clo`).
+
 ## dependencies
 
 This project was tested on macOS.
@@ -45,7 +49,7 @@ This project was tested on macOS.
 
 ```
 make -C src/ release
-bin/clocalc <source-path>
+bin/clo <source-path>
 ```
 
 `python3 run_test.py` (re-)builds the interpreter and runs all tests.

run_test.py

@@ -37,7 +37,7 @@ def test() -> None:
                 with open(iopath, "r") as f:
                     io = json.loads(f.read())
                 start = time.time()
-                res = execute(["bin/clocalc", filepath], io["in"])
+                res = execute(["bin/clo", filepath], io["in"])
                 end = time.time()
                 if (res[0] == 0 and res[1] == io["out"]):
                     print(f"OK ({end - start:.3f} seconds)")

src/Makefile

@@ -2,7 +2,7 @@ CXX = clang++
 WARNING = -Wall -Wextra -pedantic
 STD = -std=c++20
 SRC = main.cpp
-DST = -o ../bin/clocalc
+DST = -o ../bin/clo
 
 debug: main.cpp
 	$(CXX) $(WARNING) $(STD) -g -fsanitize=address,undefined -fno-omit-frame-pointer -fno-sanitize-recover=all $(SRC) $(DST)