5001 - drop the :(scenario) DSL

I've been saying for a while[1][2][3] that adding extra abstractions makes
things harder for newcomers, and adding new notations doubly so. And then
I notice this DSL in my own backyard. Makes me feel like a hypocrite.

[1] https://news.ycombinator.com/item?id=13565743#13570092
[2] https://lobste.rs/s/to8wpr/configuration_files_are_canary_warning
[3] https://lobste.rs/s/mdmcdi/little_languages_by_jon_bentley_1986#c_3miuf2

The implementation of the DSL was also highly hacky:

a) It was happening in the tangle/ tool, but was utterly unrelated to tangling
layers.

b) There were several persnickety constraints on the different kinds of
lines and the specific order they were expected in. I kept finding bugs
where the translator would silently do the wrong thing. Or the error messages
sucked, and readers may be stuck looking at the generated code to figure
out what happened. Fixing error messages would require a lot more code,
which is one of my arguments against DSLs in the first place: they may
be easy to implement, but they're hard to design to go with the grain of
the underlying platform. They require lots of iteration. Is that effort
worth prioritizing in this project?

On the other hand, the DSL did make at least some readers' life easier,
the ones who weren't immediately put off by having to learn a strange syntax.
There were fewer quotes to parse, fewer backslash escapes.

Anyway, since there are also people who dislike having to put up with strange
syntaxes, we'll call that consideration a wash and tear this DSL out.

---

This commit was sheer drudgery. Hopefully it won't need to be redone with
a new DSL because I grow sick of backslashes.

1 files changed, 92 insertions, 52 deletions

diff --git a/019type_abbreviations.cc b/019type_abbreviations.cc
index dfa214c9..35cc5d90 100644
--- a/019type_abbreviations.cc
+++ b/019type_abbreviations.cc
@@ -1,12 +1,16 @@
 //: For convenience, allow Mu types to be abbreviated.
 
-:(scenarios transform)
-:(scenario type_abbreviations)
-type foo = number
-def main [
-  a:foo <- copy 34
-]
-+transform: product type after expanding abbreviations: "number"
+void test_type_abbreviations() {
+  transform(
+      "type foo = number\n"
+      "def main [\n"
+      "  a:foo <- copy 34\n"
+      "]\n"
+  );
+  CHECK_TRACE_CONTENTS(
+      "transform: product type after expanding abbreviations: \"number\"\n"
+  );
+}
 
 :(before "End Globals")
 map<string, type_tree*> Type_abbreviations, Type_abbreviations_snapshot;
@@ -69,33 +73,58 @@ string_tree* parse_string_list(const string& s) {
   return parse_property_list(in);
 }
 
-:(scenario type_error1)
-% Hide_errors = true;
-type foo
-+error: incomplete 'type' statement 'type foo'
+void test_type_error1() {
+  Hide_errors = true;
+  transform(
+      "type foo\n"
+  );
+  CHECK_TRACE_CONTENTS(
+      "error: incomplete 'type' statement 'type foo'\n"
+  );
+}
 
-:(scenario type_error2)
-% Hide_errors = true;
-type foo =
-+error: incomplete 'type' statement 'type foo ='
+void test_type_error2() {
+  Hide_errors = true;
+  transform(
+      "type foo =\n"
+  );
+  CHECK_TRACE_CONTENTS(
+      "error: incomplete 'type' statement 'type foo ='\n"
+  );
+}
 
-:(scenario type_error3)
-% Hide_errors = true;
-type foo bar baz
-+error: 'type' statements must be of the form 'type <new type name> = <type expression>' but got 'type foo bar'
+void test_type_error3() {
+  Hide_errors = true;
+  transform(
+      "type foo bar baz\n"
+  );
+  CHECK_TRACE_CONTENTS(
+      "error: 'type' statements must be of the form 'type <new type name> = <type expression>' but got 'type foo bar'\n"
+  );
+}
 
-:(scenario type_conflict_error)
-% Hide_errors = true;
-type foo = bar
-type foo = baz
-+error: 'type' conflict: 'foo' defined as both 'bar' and 'baz'
+void test_type_conflict_error() {
+  Hide_errors = true;
+  transform(
+      "type foo = bar\n"
+      "type foo = baz\n"
+  );
+  CHECK_TRACE_CONTENTS(
+      "error: 'type' conflict: 'foo' defined as both 'bar' and 'baz'\n"
+  );
+}
 
-:(scenario type_abbreviation_for_compound)
-type foo = address:number
-def main [
-  1:foo <- copy null
-]
-+transform: product type after expanding abbreviations: ("address" "number")
+void test_type_abbreviation_for_compound() {
+  transform(
+      "type foo = address:number\n"
+      "def main [\n"
+      "  1:foo <- copy null\n"
+      "]\n"
+  );
+  CHECK_TRACE_CONTENTS(
+      "transform: product type after expanding abbreviations: (\"address\" \"number\")\n"
+  );
+}
 
 //: cleaning up type abbreviations between tests and before exiting
 
@@ -129,33 +158,44 @@ put(Type_abbreviations, "num", new_type_tree("number"));
 put(Type_abbreviations, "bool", new_type_tree("boolean"));
 put(Type_abbreviations, "char", new_type_tree("character"));
 
-:(scenario use_type_abbreviations_when_declaring_type_abbreviations)
-type foo = &:num
-def main [
-  1:foo <- copy null
-]
-+transform: product type after expanding abbreviations: ("address" "number")
+:(code)
+void test_use_type_abbreviations_when_declaring_type_abbreviations() {
+  transform(
+      "type foo = &:num\n"
+      "def main [\n"
+      "  1:foo <- copy null\n"
+      "]\n"
+  );
+  CHECK_TRACE_CONTENTS(
+      "transform: product type after expanding abbreviations: (\"address\" \"number\")\n"
+  );
+}
 
 //:: Expand type aliases before running.
 //: We'll do this in a transform so that we don't need to define abbreviations
 //: before we use them.
 
-:(scenario abbreviations_for_address_and_array)
-def main [
-  f 1:&:num  # abbreviation for 'address:number'
-  f 2:@:num  # abbreviation for 'array:number'
-  f 3:&:@:num  # combining '&' and '@'
-  f 4:&:&:@:&:@:num  # ..any number of times
-  f {5: (array (& num) 3)}  # support for dilated reagents and more complex parse trees
-]
-def f [
-]
-+transform: --- expand type abbreviations in recipe 'main'
-+transform: ingredient type after expanding abbreviations: ("address" "number")
-+transform: ingredient type after expanding abbreviations: ("array" "number")
-+transform: ingredient type after expanding abbreviations: ("address" "array" "number")
-+transform: ingredient type after expanding abbreviations: ("address" "address" "array" "address" "array" "number")
-+transform: ingredient type after expanding abbreviations: ("array" ("address" "number") "3")
+void test_abbreviations_for_address_and_array() {
+  transform(
+      "def main [\n"
+      "  f 1:&:num\n"  // abbreviation for 'address:number'
+      "  f 2:@:num\n"  // abbreviation for 'array:number'
+      "  f 3:&:@:num\n"  // combining '&' and '@'
+      "  f 4:&:&:@:&:@:num\n"  // ..any number of times
+      "  f {5: (array (& num) 3)}\n"  // support for dilated reagents and more complex parse trees
+      "]\n"
+      "def f [\n"
+      "]\n"
+  );
+  CHECK_TRACE_CONTENTS(
+      "transform: --- expand type abbreviations in recipe 'main'\n"
+      "transform: ingredient type after expanding abbreviations: (\"address\" \"number\")\n"
+      "transform: ingredient type after expanding abbreviations: (\"array\" \"number\")\n"
+      "transform: ingredient type after expanding abbreviations: (\"address\" \"array\" \"number\")\n"
+      "transform: ingredient type after expanding abbreviations: (\"address\" \"address\" \"array\" \"address\" \"array\" \"number\")\n"
+      "transform: ingredient type after expanding abbreviations: (\"array\" (\"address\" \"number\") \"3\")\n"
+  );
+}
 
 :(before "Transform.push_back(update_instruction_operations)")
 Transform.push_back(expand_type_abbreviations);  // idempotent