tisp

commit 9999dbbba7e3594c099d442834d4a2b38aa4fc9f
parent 99e99fe8625352b98aa4e1d20e59e67b8d8fd992
Author: Ed van Bruggen <edvb@uw.edu>
Date:   Thu, 24 Oct 2019 12:23:47 -0700

Add set! primitive

Diffstat:
test.c
 | 
34
+++++++++++++++++++++-------------
tisp.c
 | 
23
+++++++++++++++++++++++

2 files changed, 44 insertions(+), 13 deletions(-)
diff --git a/test.c b/test.c
@@ -163,22 +163,30 @@ char *tests[][2] = {
 	{ "(= '((1 2) 3 4) '((1 2) 3 4))",               "t"  },
 	{ "(= '((1 b) 3 4) '((1 2) 3 4))",               "()" },
 
-	{ "define",                      NULL },
-	{ "(define foo 4)",              ""   },
-	{ "foo",                         "4"  },
-	{ "(define bar foo)",            ""   },
-	{ "bar",                         "4"  },
-	{ "(define add +)",              ""   },
-	{ "(add foo bar)",               "8"  },
-	{ "(define (one x) (add x 1))",  ""   },
-	{ "(one foo)",                   "5"  },
+	{ "define",                      NULL    },
+	{ "(define foo 4)",              ""      },
+	{ "foo",                         "4"     },
+	{ "(define bar foo)",            ""      },
+	{ "bar",                         "4"     },
+	{ "(set! foo 5)",                ""      },
+	{ "foo",                         "5"     },
+	{ "(set! foo (+ foo bar))",      ""      },
+	{ "foo",                         "9"     },
+	{ "(define add +)",              ""      },
+	{ "(add foo bar)",               "13"    },
+	{ "(define (one x) (add x 1))",  ""      },
+	{ "(one foo)",                   "10"    },
 	{ "(define (more x)"
 	  "        (define term 3)"
-	  "        (+ x term))",         ""   },
-	{ "(more 8)",                    "11" },
+	  "        (+ x term))",         ""      },
+	{ "(more 8)",                    "11"    },
 	{ "(define (add2 x)"
-	  "        (+ x 1) (+ x 2))",    ""   },
-	{ "(add2 2)",                    "4"  },
+	  "        (+ x 1) (+ x 2))",    ""      },
+	{ "(add2 2)",                    "4"     },
+	{ "(set! add2 2)",               ""      },
+	{ "add2",                        "2"     },
+	{ "(set! add2 \"2\")",           ""      },
+	{ "add2",                        "\"2\"" },
 
 	{ "lambda",                       NULL },
 	{ "((lambda (x) x) 3)",           "3"  },
diff --git a/tisp.c b/tisp.c
@@ -948,6 +948,28 @@ prim_define(Env env, Val args)
 	return env->none;
 }
 
+static Val
+prim_set(Env env, Val args)
+{
+	Val val;
+	Hash h;
+	Entry e = NULL;
+	tsp_arg_num(args, "set!", 2);
+	tsp_arg_type(car(args), "set!", SYMBOL);
+	if (!(val = tisp_eval(env, cadr(args))))
+		return NULL;
+	/* find first occurrence of symbol */
+	for (h = env->h; h; h = h->next) {
+		e = entry_get(h, car(args)->v.s);
+		if (e->key)
+			break;
+	}
+	if (!e || !e->key)
+		tsp_warnf("set!: variable %s is not defined", car(args)->v.s);
+	e->val = val;
+	return env->none;
+}
+
 /* loads tisp file or C dynamic library */
 static Val
 prim_load(Env env, Val args)
@@ -1071,6 +1093,7 @@ tisp_env_init(size_t cap)
 	tsp_env_fn(lambda);
 	tsp_env_fn(macro);
 	tsp_env_fn(define);
+	tsp_env_name_fn(set!, set);
 	tsp_env_fn(load);
 	tsp_env_fn(error);
 	tsp_env_fn(version);