Changeset 1689 for lang/unlambda

Timestamp:

11/17/07 02:03:23 (12 months ago)

Author:

nishio

Message:

lang/unlambda/impl/in_python: support [d], the delay special form; add docstrings

Files:

• lang/unlambda/impl/in_python/unlambda.py (modified) (6 diffs)

lang/unlambda/impl/in_python/unlambda.py

@@ -22 +22 @@
     
 class Apply(Node):
+    "apply: `FG = F(G)"
     def __init__(self, f, g):
         self.f = f
         self.g = g
     def eval(self):
-        return self.f.eval()(self.g.eval())
+        f, g = self.f, self.g
+        if f == "(delay)": # special form
+            def Promise0(Y):
+                g.eval()
+                def Promise1(X):
+                    return X(Y)
+                return Promise1
+            return Promise0
+        return f.eval()(g.eval())
 
 class Dot(Node):
+    "print char: `.aX => print 'a'"
     def __init__(self, c):
         self.c = c
@@ -35 +45 @@
             import sys
             sys.stdout.write(self.c)
+            return X
         return Dot0
 
 class R(Node):
+    "carriage return: `rX => newline"
     def eval(self):
         def R0(X):
             print
+            return X
         return R0
 
 class K(Node):
+    "constant: ``kXY = X"
     def eval(self):
         def K0(X):
@@ -52 +66 @@
 
 class S(Node):
+    "substitution: ```sXYZ = ``XZ`YZ"
     def eval(self):
         def S0(X):
@@ -62 +77 @@
 
 class I(Node):
+    "identity"
     def eval(self):
         def I0(X):
@@ -68 +84 @@
 
 class V(Node):
-    """blackhole: v(x) == v
+    """void: v(x) == v
     equivalent to ` ``s``s`kskk ``s``s`kskk"""
     def eval(self):
@@ -85 +101 @@
         "r": lambda: R(),
         "v": lambda: V(),
+        "d": lambda: "(delay)", # special form
     }.get(c, lambda: _parse(iter))()
     return result