Merge branch 'master' of https://github.com/GrammaticalFramework/gf-core

2 files changed, 51 insertions, 44 deletions

diff --git a/doc/gf-video-tutorials.md b/doc/gf-video-tutorials.md
new file mode 100644
index 000000000..72acce26e
--- /dev/null
+++ b/doc/gf-video-tutorials.md
@@ -0,0 +1,35 @@
+---
+title: "Video tutorials"
+---
+
+The GF [YouTube channel](https://www.youtube.com/channel/UCZ96DechSUVcXAhtOId9VVA) keeps a playlist of [all GF videos](https://www.youtube.com/playlist?list=PLrgqBB5thLeT15fUtJ8_Dtk8ppdtH90MK), and more specific playlists for narrower topics.
+If you make a video about GF, let us know and we'll add it to the suitable playlist(s)!
+
+- [General introduction to GF](#general-introduction-to-gf)
+- [Beginner resources](#beginner-resources)
+- [Resource grammar tutorials](#resource-grammar-tutorials)
+
+## General introduction to GF
+
+These videos introduce GF at a high level, and present some use cases.
+
+__Grammatical Framework: Formalizing the Grammars of the World__
+
+<iframe width="560" height="315" src="https://www.youtube-nocookie.com/embed/x1LFbDQhbso" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
+
+__Aarne Ranta: Automatic Translation for Consumers and Producers__
+
+<iframe width="560" height="315" src="https://www.youtube-nocookie.com/embed/An-AmFScw1o" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
+
+## Beginner resources
+
+These videos show how to install GF on your computer (Mac or Windows), and how to play with simple grammars in a [Jupyter notebook](https://github.com/GrammaticalFramework/gf-binder) (any platform, hosted at [mybinder.org](https://mybinder.org)).
+
+<iframe width="560" height="315" src="https://www.youtube-nocookie.com/embed/videoseries?list=PLrgqBB5thLeRa8eViJJnjT8jBhxqCPMF2" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
+
+## Resource grammar tutorials
+
+These videos show incremental improvements to a [miniature version of the resource grammar](https://github.com/inariksit/comp-syntax-2020/tree/master/lab2/grammar/dummy#readme).
+They assume some prior knowledge of GF, roughly lessons 1-3 from the [GF tutorial](http://www.grammaticalframework.org/doc/tutorial/gf-tutorial.html).
+
+<iframe width="560" height="315" src="https://www.youtube-nocookie.com/embed/videoseries?list=PLrgqBB5thLeTPkp88lnOmRtprCa8g0wX2" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
diff --git a/doc/tutorial/gf-tutorial.t2t b/doc/tutorial/gf-tutorial.t2t
index 525749822..7467e107e 100644
--- a/doc/tutorial/gf-tutorial.t2t
+++ b/doc/tutorial/gf-tutorial.t2t
@@ -898,7 +898,7 @@ Parentheses are only needed for grouping.
 Parsing something that is not in grammar will fail:
 ```
   > parse "hello dad"
-  Unknown words: dad
+  The parser failed at token 2: "dad"
 
   > parse "world hello"
   no tree found
@@ -2948,7 +2948,7 @@ We need the following combinations:
 ```
 We also need **lexical insertion**, to form phrases from single words:
 ```
-  mkCN : N -> NP ;
+  mkCN : N -> CN ;
   mkAP : A -> AP ;
 ```
 Naming convention: to construct a //C//, use a function ``mk``//C//.
@@ -2969,7 +2969,7 @@ can be built as follows:
 ```
   mkCl
     (mkNP these_Det
-       (mkCN (mkAP very_AdA (mkAP warm_A)) (mkCN pizza_CN)))
+       (mkCN (mkAP very_AdA (mkAP warm_A)) (mkCN pizza_N)))
     (mkAP italian_AP)
 ```
 The task now: to define the concrete syntax of ``Foods`` so that
@@ -3718,49 +3718,25 @@ Concrete syntax does not know if a category is a dependent type.
 ```
 Notice that the ``Kind`` argument is suppressed in linearization.
 
-Parsing with dependent types is performed in two phases:
+Parsing with dependent types consists of two phases:
 + context-free parsing
 + filtering through type checker
 
+Parsing a type-correct command works as expected:
 
-By just doing the first phase, the ``kind`` argument is not found:
 ```
   > parse "dim the light"
-  CAction ? dim (DKindOne light)
-```
-Moreover, type-incorrect commands are not rejected:
-```
-  > parse "dim the fan"
-  CAction ? dim (DKindOne fan)
-```
-The term ``?`` is a **metavariable**, returned by the parser
-for any subtree that is suppressed by a linearization rule.
-These are the same kind of metavariables as were used #Rsecediting
-to mark incomplete parts of trees in the syntax editor.
-
-
-
-#NEW
-
-===Solving metavariables===
-
-Use the command ``put_tree = pt`` with the option ``-typecheck``:
-```
-  > parse "dim the light" | put_tree -typecheck
   CAction light dim (DKindOne light)
 ```
-The ``typecheck`` process may fail, in which case an error message
-is shown and no tree is returned:
+However, type-incorrect commands are rejected by the typecheck:
 ```
-  > parse "dim the fan" | put_tree -typecheck
-
-  Error in tree UCommand (CAction ? 0 dim (DKindOne fan)) :
-    (? 0 <> fan) (? 0 <> light)
+  > parse "dim the fan"
+  The parsing is successful but the type checking failed with error(s):
+    Couldn't match expected type Device light
+       against the interred type Device fan
+    In the expression: DKindOne fan       
 ```
 
-
-
-
 #NEW
 
 ==Polymorphism==
@@ -3786,23 +3762,19 @@ to express Haskell-type library functions:
     \_,_,_,f,x,y -> f y x ;
 ```
 
-
 #NEW
 
 ===Dependent types: exercises===
 
 1. Write an abstract syntax module with above contents
 and an appropriate English concrete syntax. Try to parse the commands
-//dim the light// and //dim the fan//, with and without ``solve`` filtering.
-
+//dim the light// and //dim the fan//.
 
-2. Perform random and exhaustive generation, with and without
-``solve`` filtering.
+2. Perform random and exhaustive generation.
 
 3. Add some device kinds and actions to the grammar.
 
 
-
 #NEW
 
 ==Proof objects==
@@ -3912,7 +3884,6 @@ fun
 Classes for new actions can be added incrementally.
 
 
-
 #NEW
 
 ==Variable bindings==
@@ -4200,7 +4171,8 @@ We construct a calculator with addition, subtraction, multiplication, and
 division of integers.
 ```
   abstract Calculator = {
-
+  flags startcat = Exp ;
+  
   cat Exp ;
 
   fun
@@ -4226,7 +4198,7 @@ We begin with a
 concrete syntax that always uses parentheses around binary
 operator applications:
 ```
-  concrete CalculatorP of Calculator = {
+  concrete CalculatorP of Calculator = open Prelude in {
 
   lincat
     Exp = SS ;