[MOREL-37] Raise exceptions in built-in functions

Built-in functions now raise exceptions Empty, Size, Subscript. (It is not yet possible to define, raise or handle exceptions in user code.) Move class ComparableSingletonList to top-level.
hydromatic · May 12, 2020 · 0cedd58 · 0cedd58
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commit 0cedd58
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Showing 13 changed files with 375 additions and 131 deletions.
diff --git a/src/main/java/net/hydromatic/morel/compile/BuiltIn.java b/src/main/java/net/hydromatic/morel/compile/BuiltIn.java
@@ -55,10 +55,6 @@ public enum BuiltIn {
   /** Function "abs", of type "int &rarr; int". */
   ABS(null, "abs", ts -> ts.fnType(INT, INT)),
 
-  /** Function "ignore", of type "&alpha; &rarr; unit". */
-  IGNORE(null, "ignore", ts ->
-      ts.forallType(1, h -> ts.fnType(h.get(0), UNIT))),
-
   /** Infix operator "^", of type "string * string &rarr; string". */
   OP_CARET(null, "op ^", ts -> ts.fnType(ts.tupleType(STRING, STRING), STRING)),
 
@@ -170,6 +166,10 @@ public enum BuiltIn {
       ts.forallType(1, h ->
           ts.fnType(ts.tupleType(h.get(0), h.get(0)), h.get(0)))),
 
+  /** Function "General.ignore", of type "&alpha; &rarr; unit". */
+  IGNORE("General", "ignore", "ignore", ts ->
+      ts.forallType(1, h -> ts.fnType(h.get(0), UNIT))),
+
   /** Operator "General.op o", of type "(&beta; &rarr; &gamma;) *
    * (&alpha; &rarr; &beta;) &rarr; &alpha; &rarr; &gamma;"
    *
@@ -195,7 +195,9 @@ public enum BuiltIn {
   /** Function "String.sub", of type "string * int &rarr; char".
    *
    * <p>"sub (s, i)" returns the i(th) character of s, counting from zero. This
-   * raises {@code Subscript} if i &lt; 0 or |s| &le; i. */
+   * raises
+   * {@link net.hydromatic.morel.eval.Codes.BuiltInExn#SUBSCRIPT Subscript}
+   * if i &lt; 0 or |s| &le; i. */
   STRING_SUB("String", "sub", ts -> ts.fnType(ts.tupleType(STRING, INT), CHAR)),
 
   /** Function "String.extract", of type "string * int * int option &rarr;
@@ -205,13 +207,15 @@ public enum BuiltIn {
    *
    * <p>"extract (s, i, NONE)" and "extract (s, i, SOME j)" return substrings of
    * s. The first returns the substring of s from the i(th) character to the end
-   * of the string, i.e., the string s[i..|s|-1]. This raises {@code Subscript}
+   * of the string, i.e., the string s[i..|s|-1]. This raises
+   * {@link net.hydromatic.morel.eval.Codes.BuiltInExn#SUBSCRIPT Subscript}
    * if i &lt; 0 * or |s| &lt; i.
    *
    * <p>The second form returns the substring of size j starting at index i,
-   * i.e., the string s[i..i+j-1]. It raises {@code Subscript} if i &lt; 0 or j
-   * &lt; 0 or |s| &lt; i + j. Note that, if defined, extract returns the empty
-   * string when i = |s|. */
+   * i.e., the string s[i..i+j-1]. It raises
+   * {@link net.hydromatic.morel.eval.Codes.BuiltInExn#SUBSCRIPT Subscript}
+   * if i &lt; 0 or j &lt; 0 or |s| &lt; i + j. Note that, if defined, extract
+   * returns the empty string when i = |s|. */
   STRING_EXTRACT("String", "extract", ts ->
       ts.fnType(ts.tupleType(STRING, INT), STRING)),
 
@@ -226,16 +230,18 @@ public enum BuiltIn {
   /** Function "String.concat", of type "string list &rarr; string".
    *
    * <p>"concat l" is the concatenation of all the strings in l. This raises
-   * {@code Size} if the sum of all the sizes is greater than maxSize.  */
+   * {@link net.hydromatic.morel.eval.Codes.BuiltInExn#SIZE Size}
+   * if the sum of all the sizes is greater than maxSize.  */
   STRING_CONCAT("String", "concat", ts ->
       ts.fnType(ts.listType(STRING), STRING)),
 
   /** Function "String.concatWith", of type "string &rarr; string list &rarr;
    * string".
    *
    * <p>"concatWith s l" returns the concatenation of the strings in the list l
-   * using the string s as a separator. This raises {@code Size} if the size of
-   * the resulting string would be greater than maxSize. */
+   * using the string s as a separator. This raises
+   * {@link net.hydromatic.morel.eval.Codes.BuiltInExn#SIZE Size}
+   * if the size of the resulting string would be greater than maxSize. */
   STRING_CONCAT_WITH("String", "concatWith", ts ->
       ts.fnType(STRING, ts.listType(STRING), STRING)),
 
@@ -247,7 +253,8 @@ public enum BuiltIn {
   /** Function "String.implode", of type "char list &rarr; string".
    *
    * <p>"implode l" generates the string containing the characters in the list
-   * l. This is equivalent to concat (List.map str l). This raises {@code Size}
+   * l. This is equivalent to {@code concat (List.map str l)}. This raises
+   * {@link net.hydromatic.morel.eval.Codes.BuiltInExn#SIZE Size}
    * if the resulting string would have size greater than maxSize. */
   STRING_IMPLODE("String", "implode", ts ->
       ts.fnType(ts.listType(CHAR), STRING)),
@@ -339,24 +346,27 @@ public enum BuiltIn {
 
   /** Function "List.hd", of type "&alpha; list &rarr; &alpha;".
    *
-   * <p>"hd l" returns the first element of l. It raises {@code Empty} if l is
-   * nil.
+   * <p>"hd l" returns the first element of l. It raises
+   * {@link net.hydromatic.morel.eval.Codes.BuiltInExn#EMPTY Empty}
+   * if l is nil.
    */
   LIST_HD("List", "hd", ts ->
       ts.forallType(1, h -> ts.fnType(h.list(0), h.get(0)))),
 
   /** Function "List.tl", of type "&alpha; list &rarr; &alpha; list".
    *
-   * <p>"tl l" returns all but the first element of l. It raises {@code Empty}
+   * <p>"tl l" returns all but the first element of l. It raises
+   * {@link net.hydromatic.morel.eval.Codes.BuiltInExn#EMPTY empty}
    * if l is nil.
    */
   LIST_TL("List", "tl", ts ->
       ts.forallType(1, h -> ts.fnType(h.list(0), h.list(0)))),
 
   /** Function "List.last", of type "&alpha; list &rarr; &alpha;".
    *
-   * <p>"last l" returns the last element of l. It raises {@code Empty} if l is
-   * nil.
+   * <p>"last l" returns the last element of l. It raises
+   * {@link net.hydromatic.morel.eval.Codes.BuiltInExn#EMPTY empty}
+   * if l is nil.
    */
   LIST_LAST("List", "last", ts ->
       ts.forallType(1, h -> ts.fnType(h.list(0), h.get(0)))),
@@ -366,8 +376,9 @@ public enum BuiltIn {
    *
    * <p>"getItem l" returns {@code NONE} if the list is empty, and
    * {@code SOME(hd l,tl l)} otherwise. This function is particularly useful for
-   * creating value readers from lists of characters. For example, Int.scan
-   * StringCvt.DEC getItem has the type {@code (int,char list) StringCvt.reader}
+   * creating value readers from lists of characters. For example,
+   * {@code Int.scan StringCvt.DEC getItem} has the type
+   * {@code (int, char list) StringCvt.reader}
    * and can be used to scan decimal integers from lists of characters.
    */
   // TODO: make it return an option
@@ -378,17 +389,20 @@ public enum BuiltIn {
   /** Function "List.nth", of type "&alpha; list * int &rarr; &alpha;".
    *
    * <p>"nth (l, i)" returns the i(th) element of the list l, counting from 0.
-   * It raises {@code Subscript} if i &lt; 0 or i &ge; length l. We have
-   * nth(l,0) = hd l, ignoring exceptions.
+   * It raises
+   * {@link net.hydromatic.morel.eval.Codes.BuiltInExn#SUBSCRIPT Subscript}
+   * if i &lt; 0 or i &ge; length l.
+   * We have {@code nth(l,0) = hd l}, ignoring exceptions.
    */
   LIST_NTH("List", "nth", ts ->
       ts.forallType(1, h -> ts.fnType(ts.tupleType(h.list(0), INT), h.get(0)))),
 
   /** Function "List.take", of type "&alpha; list * int &rarr; &alpha; list".
    *
    * <p>"take (l, i)" returns the first i elements of the list l. It raises
-   * {@code Subscript} if i &lt; 0 or i &gt; length l.
-   * We have take(l, length l) = l.
+   * {@link net.hydromatic.morel.eval.Codes.BuiltInExn#SUBSCRIPT Subscript}
+   * if i &lt; 0 or i &gt; length l.
+   * We have {@code take(l, length l) = l}.
    */
   LIST_TAKE("List", "take", ts ->
       ts.forallType(1, h ->
@@ -399,7 +413,9 @@ public enum BuiltIn {
    * <p>"drop (l, i)" returns what is left after dropping the first i elements
    * of the list l.
    *
-   * <p>It raises {@code Subscript} if i &lt; 0 or i &gt; length l.
+   * <p>It raises
+   * {@link net.hydromatic.morel.eval.Codes.BuiltInExn#SUBSCRIPT Subscript}
+   * if i &lt; 0 or i &gt; length l.
    *
    * <p>It holds that
    * {@code take(l, i) @ drop(l, i) = l} when 0 &le; i &le; length l.
@@ -552,7 +568,8 @@ public enum BuiltIn {
    *
    * <p>"tabulate (n, f)" returns a list of length n equal to
    * {@code [f(0), f(1), ..., f(n-1)]}, created from left to right. It raises
-   * {@code Size} if n &lt; 0.
+   * {@link net.hydromatic.morel.eval.Codes.BuiltInExn#SIZE Size}
+   * if n &lt; 0.
    */
   LIST_TABULATE("List", "tabulate", ts ->
       ts.forallType(1, h ->

diff --git a/src/main/java/net/hydromatic/morel/compile/Compiler.java b/src/main/java/net/hydromatic/morel/compile/Compiler.java
@@ -35,12 +35,12 @@
 import net.hydromatic.morel.type.ListType;
 import net.hydromatic.morel.type.RecordType;
 import net.hydromatic.morel.type.Type;
+import net.hydromatic.morel.util.ComparableSingletonList;
 import net.hydromatic.morel.util.Ord;
 import net.hydromatic.morel.util.Pair;
 import net.hydromatic.morel.util.TailList;
 
 import java.math.BigDecimal;
-import java.util.AbstractList;
 import java.util.ArrayList;
 import java.util.IdentityHashMap;
 import java.util.LinkedHashMap;
@@ -480,7 +480,7 @@ private void compileTyCon(Environment env, Type dataType,
     final Type type = Objects.requireNonNull(typeMap.getType(tyCon));
     final Object value;
     if (tyCon.type == null) {
-      value = Codes.constant(new ComparableSingletonList<>(tyCon.id.name));
+      value = Codes.constant(ComparableSingletonList.of(tyCon.id.name));
     } else {
       value = Codes.tyCon(dataType, tyCon.id.name);
     }
@@ -609,10 +609,14 @@ private void compileValBind(Environment env, Ast.ValBind valBind,
       final Type type0 = typeMap.getType(valBind.e);
       final Type type = typeMap.typeSystem.ensureClosed(type0);
       actions.add((output, outBindings, evalEnv) -> {
-        final Object o = code.eval(evalEnv);
-        outBindings.add(Binding.of(name, type, o));
         final StringBuilder buf = new StringBuilder();
-        Pretty.pretty(buf, type, new Pretty.TypedVal(name, o, type0));
+        try {
+          final Object o = code.eval(evalEnv);
+          outBindings.add(Binding.of(name, type, o));
+          Pretty.pretty(buf, type, new Pretty.TypedVal(name, o, type0));
+        } catch (Codes.MorelRuntimeException e) {
+          e.describeTo(buf);
+        }
         output.add(buf.toString());
       });
     }
@@ -649,33 +653,6 @@ public Object eval(EvalEnv env) {
       return refCode.eval(env);
     }
   }
-
-  /** A comparable singleton list.
-   *
-   * @param <E> Element type */
-  private static class ComparableSingletonList<E extends Comparable<E>>
-      extends AbstractList<E>
-      implements Comparable<ComparableSingletonList<E>> {
-    private final E element;
-
-    ComparableSingletonList(E element) {
-      this.element = Objects.requireNonNull(element);
-    }
-
-    @Override public E get(int index) {
-      assert index == 0;
-      return element;
-    }
-
-    @Override public int size() {
-      return 1;
-    }
-
-    @Override public int compareTo(ComparableSingletonList<E> o) {
-      return element.compareTo(o.element);
-    }
-  }
-
 }
 
 // End Compiler.java
diff --git a/src/main/java/net/hydromatic/morel/compile/Pretty.java b/src/main/java/net/hydromatic/morel/compile/Pretty.java
@@ -19,6 +19,7 @@
 package net.hydromatic.morel.compile;
 
 import net.hydromatic.morel.foreign.RelList;
+import net.hydromatic.morel.type.DataType;
 import net.hydromatic.morel.type.ForallType;
 import net.hydromatic.morel.type.ListType;
 import net.hydromatic.morel.type.PrimitiveType;
@@ -239,6 +240,20 @@ private static StringBuilder pretty2(@Nonnull StringBuilder buf,
       return pretty2(buf, indent, lineEnd, depth + 1, ((ForallType) type).type,
           value);
 
+    case DATA_TYPE:
+      final DataType dataType = (DataType) type;
+      //noinspection unchecked
+      list = (List) value;
+      final String tyConName = (String) list.get(0);
+      buf.append(tyConName);
+      final Type typeConArgType = dataType.typeConstructors.get(tyConName);
+      if (list.size() == 2) {
+        final Object arg = list.get(1);
+        buf.append(' ');
+        pretty2(buf, indent, lineEnd, depth + 1, typeConArgType, arg);
+      }
+      return buf;
+
     default:
       return buf.append(value);
     }

diff --git a/src/main/java/net/hydromatic/morel/compile/TypeMap.java b/src/main/java/net/hydromatic/morel/compile/TypeMap.java
@@ -21,6 +21,7 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSortedMap;
+import com.google.common.collect.Lists;
 
 import net.hydromatic.morel.ast.AstNode;
 import net.hydromatic.morel.type.RecordType;
@@ -131,7 +132,12 @@ public Type visit(Unifier.Sequence sequence) {
       default:
         final Type type = typeMap.typeSystem.lookupOpt(sequence.operator);
         if (type != null) {
-          return type;
+          if (sequence.terms.isEmpty()) {
+            return type;
+          }
+          final List<Type> types =
+              Lists.transform(sequence.terms, t -> t.accept(this));
+          return typeMap.typeSystem.apply(type, types);
         }
         if (sequence.operator.startsWith(TypeResolver.RECORD_TY_CON)) {
           // E.g. "record:a:b" becomes record type "{a:t0, b:t1}".