Added step0_repl.ts

step0_repl.ts

@@ -0,0 +1,36 @@
+function read(source: string): string {
+    return source;
+}
+
+function eval_(ast: string): string {
+    return ast;
+}
+
+function print(form: string): string {
+    return form
+}
+
+function rep(source: string): string{
+    return print(eval_(read( source)))
+}
+
+function* readUserInputs(): Generator<string>{
+    while(true){
+        const u =  prompt("user> ")
+        if(u === null){
+            return
+        }
+        yield u
+    }
+}
+
+
+function main(): void {
+     for(const userInput of readUserInputs()){
+         rep(userInput);
+     }
+
+
+}
+
+main();