Activations LeakyReLU / PReLU / Softplus / Mish (#109)

* Leaky_relu / prelu / softplus / mish

* added tests

* updated bench

* remove torch refs, add init to PReLU

* added arvix reference to mish

* added missing docs

benchmarks/python/comparative/bench_mlx.py

@@ -96,7 +96,35 @@ def softmax_fused(axis, x):
 def relu(x):
     y = x
     for i in range(100):
-        y = mx.maximum(y, 0)
+        y = nn.relu(y)
+    mx.eval(y)
+
+
+def leaky_relu(x: mx.array):
+    y = x
+    for i in range(100):
+        y = nn.leaky_relu(y)
+    mx.eval(y)
+
+
+def prelu(x: mx.array):
+    y = x
+    for i in range(100):
+        y = nn.prelu(y, mx.ones(1))
+    mx.eval(y)
+
+
+def softplus(x: mx.array):
+    y = x
+    for i in range(100):
+        y = nn.softplus(y)
+    mx.eval(y)
+
+
+def mish(x: mx.array):
+    y = x
+    for i in range(100):
+        y = nn.mish(y)
     mx.eval(y)
 
 
@@ -334,24 +362,26 @@ if __name__ == "__main__":
     elif args.benchmark == "relu":
         print(bench(relu, x))
 
-    elif args.benchmark == "leaky_relu":
-        print(bench(leaky_relu, x))
-
     elif args.benchmark == "elu":
         print(bench(elu, x))
 
     elif args.benchmark == "relu6":
         print(bench(relu6, x))
 
-    elif args.benchmark == "softplus":
-        print(bench(softplus, x))
-
     elif args.benchmark == "celu":
         print(bench(celu, x))
 
     elif args.benchmark == "log_sigmoid":
         print(bench(log_sigmoid, x))
 
+    elif args.benchmark == "leaky_relu":
+        print(bench(leaky_relu, x))
+    elif args.benchmark == "prelu":
+        print(bench(prelu, x))
+    elif args.benchmark == "softplus":
+        print(bench(softplus, x))
+    elif args.benchmark == "mish":
+        print(bench(mish, x))
     elif args.benchmark == "scalar_mul":
         print(bench(scalar_mult, x))