fixup! Add at-par macro

docs/src/index.md

@@ -42,6 +42,19 @@ s = @par combine(p, q, r)
 @assert collect(s) == 16
 ```
 
+or similarly:
+
+```julia
+s = @par begin
+    p = add1(4)
+    q = add2(p)
+    r = add1(3)
+    combine(p, q, r)
+end
+
+@assert collect(s) == 16
+```
+
 The connections between nodes `p`, `q`, `r` and `s` is represented by this dependency graph:
 
 ![graph](https://user-images.githubusercontent.com/25916/26920104-7b9b5fa4-4c55-11e7-97fb-fe5b9e73cae6.png)

src/thunk.jl

@@ -79,14 +79,38 @@ delayedmap(f, xs...) = map(delayed(f), xs...)
     @par f(args...) -> Thunk
 
 Convenience macro to call `Dagger.delayed` on `f` with arguments `args`.
+May also be called with a series of assignments like so:
+
+```julia
+x = @par begin
+    a = f(1,2)
+    b = g(a,3)
+    h(a,b)
+end
+```
+
+`x` will hold the Thunk representing `h(a,b)`; additionally, `a` and `b`
+will be defined in the same local scope and will be equally accessible
+for later calls.
 """
 macro par(ex)
-    @assert ex.head == :call "@par requires a function call as the argument"
-    f = ex.args[1]
-    args = ex.args[2:end]
-    # TODO: Support kwargs
-    :(Dagger.delayed(f)($(args...)))
+    _ex = _par(ex)
+    dump(_ex)
+    @show _ex
+    _ex
+end
+function _par(ex::Expr)
+    if ex.head == :call
+        f = ex.args[1]
+        args = ex.args[2:end]
+        # TODO: Support kwargs
+        return :(Dagger.delayed($(esc(f)))($(_par.(args)...)))
+    else
+        return Expr(ex.head, _par.(ex.args)...)
+    end
 end
+_par(ex::Symbol) = esc(ex)
+_par(ex) = ex
 
 persist!(t::Thunk) = (t.persist=true; t)
 cache_result!(t::Thunk) = (t.cache=true; t)

test/thunk.jl

@@ -5,4 +5,15 @@
     b = @par sum([x,1,2])
     c = @par a * b
     @test collect(c) == 20
+
+    c = @par begin
+        x = 2
+        a = x + x
+        b = sum([x,1,2])
+        c = a * b
+    end
+    @test x isa Int
+    @test a isa Dagger.Thunk
+    @test c isa Dagger.Thunk
+    @test collect(c) == 20
 end