Update the parser to allow prefix operators in more places.

This allows us to define (~) as a prefix operator symbol synonym
for `complement`.

Fixes #296.

lib/Cryptol.cry

@@ -94,10 +94,16 @@ primitive False : Bit
 primitive negate : {a} (Arith a) => a -> a
 
 /**
- * Binary complement
+ * Binary complement.
  */
 primitive complement : {a} a -> a
 
+/**
+ * Operator form of binary complement.
+ */
+(~) : {a} a -> a
+(~) = complement
+
 /**
  * Less-than. Only works on comparable arguments.
  */

src/Cryptol/Parser.y

@@ -267,7 +267,8 @@ mbDoc                   :: { Maybe (Located String) }
 decl                    :: { Decl PName }
   : vars_comma ':' schema  { at (head $1,$3) $ DSignature (reverse $1) $3   }
   | ipat '=' expr          { at ($1,$3) $ DPatBind $1 $3                    }
-  | name apats '=' expr    { at ($1,$4) $
+  | '(' op ')' '=' expr    { at ($1,$5) $ DPatBind (PVar $2) $5             }
+  | var apats '=' expr     { at ($1,$4) $
                              DBind $ Bind { bName      = $1
                                           , bParams    = reverse $2
                                           , bDef       = at $4 (Located emptyRange (DExpr $4))

tests/issues/issue148.icry.stdout

@@ -5,12 +5,12 @@ Loading module Main
   Defaulting type parameter 'bits'
              of literal or demoted expression
              at ./issue148.cry:4:34--4:35
-  to max 2 (width a`193)
+  to max 2 (width a`195)
 [warning] at ./issue148.cry:2:1--9:10:
   Defaulting 2nd type parameter
              of expression take
              at ./issue148.cry:6:10--6:14
-  to 16 * a`193
+  to 16 * a`195
 [warning] at <interactive>:1:1--1:36:
   Defaulting type parameter 'bits'
              of finite enumeration

tests/issues/issue198.icry.stdout

@@ -5,15 +5,15 @@ Loading module Main
   Defaulting type parameter 'bits'
              of literal or demoted expression
              at ./simon.cry2:87:34--87:35
-  to max 3 (width a`569)
+  to max 3 (width a`571)
 [warning] at ./simon.cry2:83:1--92:15:
   Defaulting type parameter 'bits'
              of literal or demoted expression
              at ./simon.cry2:90:29--90:31
-  to width a`571
+  to width a`573
 [warning] at ./simon.cry2:83:1--92:15:
   Defaulting type parameter 'bits'
              of literal or demoted expression
              at ./simon.cry2:89:36--89:38
-  to max 6 (max (width a`569) (width (a`570 - 1)))
+  to max 6 (max (width a`571) (width (a`572 - 1)))
 True

tests/issues/issue214.icry.stdout

@@ -5,9 +5,9 @@ Loading module Main
   Defaulting type parameter 'bits'
              of finite enumeration
              at ./issue214.cry:2:14--2:26
-  to max 2 (width (2 * a`193 - 2))
+  to max 2 (width (2 * a`195 - 2))
 [warning] at ./issue214.cry:2:1--2:49:
   Defaulting type parameter 'bits'
              of finite enumeration
              at ./issue214.cry:2:36--2:48
-  to max 2 (width (2 * a`193 - 1))
+  to max 2 (width (2 * a`195 - 1))

tests/issues/issue226.icry.stdout

@@ -86,4 +86,5 @@ Symbols
                                bits >= width len) => [len]elem -> [bits]
     zero : {a} a
     (||) : {a} a -> a -> a
+    (~) : {a} a -> a
 

tests/issues/issue296.icry

@@ -0,0 +1 @@
+:t (~)

tests/issues/issue296.icry.stdout

@@ -0,0 +1,2 @@
+Loading module Cryptol
+(~) : {a} a -> a