make p,q in coe/comp optional and default to @0 @1

examples/bool.quox

@@ -17,7 +17,7 @@ def0 If : 1.Bool → 0.★₀ → 0.★₀ → ★₀ =
 def0 T : ω.Bool → ★₀ = λ b ⇒ If b True False;
 
 def true-not-false : Not ('true ≡ 'false : Bool) =
-  λ eq ⇒ coe [i ⇒ T (eq @i)] @0 @1 'true;
+  λ eq ⇒ coe [i ⇒ T (eq @i)] 'true;
 
 
 -- [todo] infix

examples/misc.quox

@@ -28,9 +28,9 @@ def funext :
   λ A P p q eq ⇒ δ 𝑖 ⇒ λ x ⇒ eq x @𝑖;
 
 def sym : 0.(A : ★₀) → 0.(x y : A) → 1.(x ≡ y : A) → y ≡ x : A =
-  λ A x y eq ⇒ δ 𝑖 ⇒ comp [A] @0 @1 (eq @0) @𝑖 { 0 𝑗 ⇒ eq @𝑗; 1 _ ⇒ eq @0 };
+  λ A x y eq ⇒ δ 𝑖 ⇒ comp [A] (eq @0) @𝑖 { 0 𝑗 ⇒ eq @𝑗; 1 _ ⇒ eq @0 };
 
 def trans : 0.(A : ★₀) → 0.(x y z : A) →
             ω.(x ≡ y : A) → ω.(y ≡ z : A) → x ≡ z : A =
   λ A x y z eq1 eq2 ⇒ δ 𝑖 ⇒
-    comp [A] @0 @1 (eq1 @𝑖) @𝑖 { 0 _ ⇒ eq1 @0; 1 𝑗 ⇒ eq2 @𝑗 };
+    comp [A] (eq1 @𝑖) @𝑖 { 0 _ ⇒ eq1 @0; 1 𝑗 ⇒ eq2 @𝑗 };

examples/nat.quox

@@ -51,7 +51,7 @@ def zero-not-succ : 0.(m : ℕ) → Not (zero ≡ succ m : ℕ) =
   λ m eq ⇒ coe [𝑖 ⇒ IsSucc (eq @𝑖)] @1 @0 'true;
 
 def succ-not-zero : 0.(m : ℕ) → Not (succ m ≡ zero : ℕ) =
-  λ m eq ⇒ coe [𝑖 ⇒ IsSucc (eq @𝑖)] @0 @1 'true;
+  λ m eq ⇒ coe [𝑖 ⇒ IsSucc (eq @𝑖)] 'true;
 
 
 def0 not-succ-self : 0.(m : ℕ) → Not (m ≡ succ m : ℕ) =

lib/Quox/Parser/Parser.idr

@@ -287,12 +287,22 @@ termArg fname = withLoc fname $
   <|> [|V qname|]
   <|> const <$> tupleTerm fname
 
+||| optionally, two dimension arguments. if absent default to `@0 @1`
+private
+optDirection : FileName -> Grammar False (PDim, PDim)
+optDirection fname = withLoc fname $ do
+  dims <- optional [|(,) (dimArg fname) (dimArg fname)|]
+  pure $ \loc => fromMaybe (K Zero loc, K One loc) dims
+
 export
 coeTerm : FileName -> Grammar True PTerm
 coeTerm fname = withLoc fname $ do
   resC "coe"
-  mustWork [|Coe (typeLine fname) (dimArg fname) (dimArg fname)
-                 (termArg fname)|]
+  mustWork $ do
+    line   <- typeLine fname
+    (p, q) <- optDirection fname
+    val    <- termArg fname
+    pure $ Coe line p q val
 
 public export
 CompBranch : Type
@@ -301,8 +311,7 @@ CompBranch = (DimConst, PatVar, PTerm)
 export
 compBranch : FileName -> Grammar True CompBranch
 compBranch fname =
-  [|(,,) dimConst (patVar fname)
-         (needRes "⇒" *> assert_total term fname)|]
+  [|(,,) dimConst (patVar fname) (needRes "⇒" *> assert_total term fname)|]
 
 private
 checkCompTermBody : (PatVar, PTerm) -> PDim -> PDim -> PTerm -> PDim ->
@@ -321,7 +330,7 @@ compTerm fname = withLoc fname $ do
   resC "comp"
   mustWork $ do
     a <- typeLine fname
-    p <- dimArg  fname; q <- dimArg fname
+    (p, q) <- optDirection fname
     s <- termArg fname; r <- dimArg fname
     bodyStart <- bounds $ needRes "{"
     s0 <- compBranch fname; needRes ";"

lib/Quox/Syntax/Term/Pretty.idr

@@ -253,6 +253,26 @@ private
 prettyCompPat : {opts : _} -> DimConst -> BindName -> Eff Pretty (Doc opts)
 prettyCompPat e x = [|prettyDimConst e <++> prettyDBind x|]
 
+private
+prettyCompArm : {opts : _} -> BContext d -> BContext n ->
+                DimConst -> DScopeTerm d n -> Eff Pretty (Doc opts)
+prettyCompArm dnames tnames e s = prettyCaseArm dnames tnames $
+  MkCaseArm !(prettyCompPat e s.name) [< s.name] [<] s.term
+
+private
+layoutComp : {opts : _} ->
+             (typq : List (Doc opts)) -> (val, r : Doc opts) ->
+             (arms : List (Doc opts)) -> Eff Pretty (Doc opts)
+layoutComp typq val r arms = do
+  comp <- compD; lb <- hl Delim "{"; rb <- hl Delim "}"
+  ind  <- askAt INDENT
+  pure $ ifMultiline
+    (hsep $ concat {t = List} [[comp], typq, [val, r, lb], arms, [rb]]) $
+    (comp <++>
+      vsep [sep typq, val, r <++> lb, indent ind $ vsep arms, rb]) <|>
+    (vsep $ (comp ::) $ map (indent ind) $ concat {t = List}
+      [typq, [val, r <++> lb], map (indent ind) arms, [rb]])
+
 
 export
 prettyTag : {opts : _} -> String -> Eff Pretty (Doc opts)
@@ -296,6 +316,12 @@ prettyCase dnames tnames qty head ret body =
   prettyCase_ dnames tnames ![|caseD <+> prettyQty qty|] head ret body
 
 
+private
+isDefaultDir : Dim d -> Dim d -> Bool
+isDefaultDir (K Zero _) (K One _) = True
+isDefaultDir _ _ = False
+
+
 -- [fixme] use telescopes in Scoped
 private
 toTel : BContext s -> BTelescope n (s + n)
@@ -477,33 +503,30 @@ prettyElim dnames tnames (Ann tm ty _) =
                 !(withPrec Outer (prettyTerm dnames tnames ty))
 
 prettyElim dnames tnames (Coe ty p q val _) =
-  parensIfM App =<< do
-    ty  <- prettyTypeLine dnames tnames ty
-    p   <- prettyDArg dnames p
-    q   <- prettyDArg dnames q
-    val <- prettyTArg dnames tnames val
-    prettyAppD !coeD [ty, sep [p, q], val]
+  parensIfM App =<<
+    if isDefaultDir p q then do
+      ty  <- prettyTypeLine dnames tnames ty
+      val <- prettyTArg dnames tnames val
+      prettyAppD !coeD [ty, val]
+    else do
+      ty  <- prettyTypeLine dnames tnames ty
+      p   <- prettyDArg dnames p
+      q   <- prettyDArg dnames q
+      val <- prettyTArg dnames tnames val
+      prettyAppD !coeD [ty, sep [p, q], val]
 
 prettyElim dnames tnames e@(Comp ty p q val r zero one _) =
   parensIfM App =<< do
     ty   <- prettyTypeLine dnames tnames $ assert_smaller e $ SN ty
-    p    <- prettyDArg dnames p
-    q    <- prettyDArg dnames q
+    pq   <- sep <$> sequence [prettyDArg dnames p, prettyDArg dnames q]
     val  <- prettyTArg dnames tnames val
     r    <- prettyDArg dnames r
-    comp <- compD; lb <- hl Delim "{"; rb <- hl Delim "}"; sc <- semiD
-    arm0 <- map (<+> sc) $ prettyCaseArm dnames tnames $
-      MkCaseArm !(prettyCompPat Zero zero.name) [< zero.name] [<] zero.term
-    arm1 <- prettyCaseArm dnames tnames $
-      MkCaseArm !(prettyCompPat One one.name) [< one.name] [<] one.term
+    arm0 <- [|prettyCompArm dnames tnames Zero zero <+> semiD|]
+    arm1 <- prettyCompArm dnames tnames One one
     ind  <- askAt INDENT
-    pure $ ifMultiline
-      (hsep [comp, ty, p, q, val, r, lb, arm0, arm1, rb])
-      (comp <++> vsep [sep [ty, sep [p, q]], val, r <++> lb,
-                       indent ind $ vsep [arm0, arm1], rb] <|>
-       vsep (comp :: map (indent ind)
-        [ty, sep [p, q], val, r <++> lb,
-         indent ind $ vsep [arm0, arm1], rb]))
+    if isDefaultDir p q
+       then layoutComp [ty]     val r [arm0, arm1]
+       else layoutComp [ty, pq] val r [arm0, arm1]
 
 prettyElim dnames tnames (TypeCase ty ret arms def _) = do
   arms <- for (toList arms) $ \(k ** body) => do

syntax.ebnf

@@ -54,10 +54,12 @@ dep eq         = "Eq", type line, term arg, term arg.
 succ           = "succ", term arg.
 normal app     = term arg, {term arg | dim arg}.
 
-coe       = "coe", type line, dim arg, dim arg, term arg.
+(* direction defaults to @0 @1 *)
+coe       = "coe", type line, [dim arg, dim arg], term arg.
 type line = "[", [pat var, "⇒"], term, "]".
 
-comp        = "comp", type line, dim arg, dim arg, term arg, dim arg, comp body.
+comp        = "comp", type line, [dim arg, dim arg],
+              term arg, dim arg, comp body.
 comp body   = "{", comp branch, ";", comp branch, [";"], "}".
 comp branch = dim const, name, "⇒", term.
 

tests/Tests/Parser.idr

@@ -290,6 +290,8 @@ tests = "parser" :- [
       `(Coe (Unused _, V "A" _) (V "p" _) (V "q" _) (V "x" _) _),
     parseMatch term "coe [i ⇒ A] @p @q x"
       `(Coe (PV "i" _, V "A" _) (V "p" _) (V "q" _) (V "x" _) _),
+    parseMatch term "coe [A] x"
+      `(Coe (Unused _, V "A" _) (K Zero _) (K One _) (V "x" _) _),
     parseFails term "coe [A] @p @q",
     parseFails term "coe A @p @q x",
     parseFails term "coe [i ⇒ A] @p q x"
@@ -299,9 +301,15 @@ tests = "parser" :- [
     parseMatch term "comp [A] @p @q s @r { 0 𝑗 ⇒ s₀; 1 𝑘 ⇒ s₁ }"
       `(Comp (Unused _, V "A" _) (V "p" _) (V "q" _) (V "s" _) (V "r" _)
           (PV "𝑗" _, V "s₀" _) (PV "𝑘" _, V "s₁" _) _),
+    parseMatch term "comp [𝑖 ⇒ A] @p @q s @r { 0 𝑗 ⇒ s₀; 1 𝑘 ⇒ s₁ }"
+      `(Comp (PV "𝑖" _, V "A" _) (V "p" _) (V "q" _) (V "s" _) (V "r" _)
+          (PV "𝑗" _, V "s₀" _) (PV "𝑘" _, V "s₁" _) _),
     parseMatch term "comp [A] @p @q s @r { 1 𝑗 ⇒ s₀; 0 𝑘 ⇒ s₁; }"
       `(Comp (Unused _, V "A" _) (V "p" _) (V "q" _) (V "s" _) (V "r" _)
           (PV "𝑘" _, V "s₁" _) (PV "𝑗" _, V "s₀" _) _),
+    parseMatch term "comp [A] s @r { 0 𝑗 ⇒ s₀; 1 𝑘 ⇒ s₁ }"
+      `(Comp (Unused _, V "A" _) (K Zero _) (K One _) (V "s" _) (V "r" _)
+          (PV "𝑗" _, V "s₀" _) (PV "𝑘" _, V "s₁" _) _),
     parseFails term "comp [A] @p @q s @r { 1 𝑗 ⇒ s₀; 1 𝑘 ⇒ s₁; }",
     parseFails term "comp [A] @p @q s @r { 0 𝑗 ⇒ s₀ }",
     parseFails term "comp [A] @p @q s @r { }"