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| author |  Adam Chlipala <adamc@hcoop.net> | 2008-10-23 12:58:35 -0400 |
|---|---|---|
| committer | Adam Chlipala <adamc@hcoop.net> | 2008-10-23 12:58:35 -0400 |
| commit | 2e606b03c8dbc594610e62ac260145ac26ebc699 (patch) | |
| tree | 23055572341487865f0ef6cff685404f796a2410 /demo | |
| parent | 3b7e65be5f6e496c23df7909d50ce8e287d571d7 (diff) | |
Fix nasty de Bruijn substitution bug; TcSum demo
Diffstat (limited to 'demo')
| -rw-r--r-- | demo/prose | 4 | ||||
| -rw-r--r-- | demo/tcSum.ur | 9 | ||||
| -rw-r--r-- | demo/tcSum.urp | 2 | ||||
| -rw-r--r-- | demo/tcSum.urs | 1 |
4 files changed, 16 insertions, 0 deletions
@@ -100,3 +100,7 @@ An unusual part of the third argument is the syntax <tt>[t1 ~ t2]</tt> within a <p>The general syntax for constant row types is <tt>[Name1 = t1, ..., NameN = tN]</tt>, and there is a shorthand version <tt>[Name1, ..., NameN]</tt> for records of <tt>Unit</tt>s.</p> <p>With <tt>sum</tt> defined, it is easy to make some sample calls. The form of the code for <tt>main</tt> does not make it apparent, but the compiler must "reverse engineer" the appropriate <tt>{Unit}</tt> from the <tt>{Type}</tt> available from the context at each call to <tt>sum</tt>.</p> + +tcSum.urp + +<p>It's easy to adapt the last example to use type classes, such that we can sum the fields of records based on any numeric type.</p> diff --git a/demo/tcSum.ur b/demo/tcSum.ur new file mode 100644 index 00000000..53679116 --- /dev/null +++ b/demo/tcSum.ur @@ -0,0 +1,9 @@ +fun sum (t ::: Type) (_ : num t) (fs ::: {Unit}) (x : $(mapUT t fs)) = + foldUR [t] [fn _ => t] + (fn (nm :: Name) (rest :: {Unit}) [[nm] ~ rest] n acc => n + acc) + zero [fs] x + +fun main () = return <xml><body> + {[sum {A = 0, B = 1}]}<br/> + {[sum {C = 2.1, D = 3.2, E = 4.3}]} +</body></xml> diff --git a/demo/tcSum.urp b/demo/tcSum.urp new file mode 100644 index 00000000..8b36efc0 --- /dev/null +++ b/demo/tcSum.urp @@ -0,0 +1,2 @@ + +tcSum diff --git a/demo/tcSum.urs b/demo/tcSum.urs new file mode 100644 index 00000000..6ac44e0b --- /dev/null +++ b/demo/tcSum.urs @@ -0,0 +1 @@ +val main : unit -> transaction page |