Added fnInput and fnOutput

2 files changed, 26 insertions, 1 deletions

diff --git a/src/compose.zig b/src/compose.zig
index 442b21b..f17dcf2 100644
--- a/src/compose.zig
+++ b/src/compose.zig
@@ -7,7 +7,7 @@ const typeVerify = @import("util.zig").typeVerify;
 /// Function composition
 /// Type signature: (a -> b) -> (b -> c) -> (a -> c)
 /// `outerFunc` and `innerFunc` are functions of types `b -> c` and `a -> b` respectively
-pub fn compose(
+pub inline fn compose(
     comptime outerFunc: anytype,
     comptime innerFunc: anytype
 ) blk:{
@@ -25,3 +25,20 @@ pub fn compose(
         }
     }.func;
 }
+
+fn testAbs(n: i32) u32 {
+    return if (n > 0) @intCast(n) else @intCast(0 - n);
+}
+
+fn testNumToString(n: u32) []const u8 {
+    var buff: [16]u8 = undefined;
+    buff[0] = std.fmt.digitToChar(@intCast(n), .lower);
+    return buff[0..1];
+}
+
+test {
+    const t = std.testing;
+    _=t;
+    const absToString = compose(testNumToString, testAbs);
+    std.debug.print("{s}\n", .{absToString(-5)});
+}
diff --git a/src/util.zig b/src/util.zig
index 8de989e..6046264 100644
--- a/src/util.zig
+++ b/src/util.zig
@@ -14,3 +14,11 @@ pub fn typeVerify(T: type, expected: anytype) Type {
         @compileError("Expected one of " ++ @tagName(e) ++ ", found " ++ @typeName(T));
     return realTypeInfo;
 }
+
+pub inline fn fnInput(f: anytype) type {
+    return typeVerify(@TypeOf(f), .{ .@"fn" }).@"fn".params[0].type.?;
+}
+
+pub inline fn fnOutput(f: anytype) type {
+    return typeVerify(@TypeOf(f), .{ .@"fn" }).@"fn".return_type.?;
+}