March 2014 update

Task/Function-composition/Applesoft-BASIC/function-composition.applesoft

@@ -0,0 +1,18 @@
+10 F$ = "SIN"
+20 DEF FN A(P) = ATN(P/SQR(-P*P+1))
+30 G$ = "FN A"
+40 GOSUB 100"COMPOSE
+50 SA$ = E$
+
+60 X = .5 : E$ = SA$
+70 GOSUB 200"EXEC
+80 PRINT R
+90 END
+
+100 E$ = F$ + "(" + G$ + "(X))" : RETURN : REMCOMPOSE F$ G$
+
+200 D$ = CHR$(4) : FI$ = "TEMPORARY.EX" : M$ = CHR$(13)
+210 PRINT D$"OPEN"FI$M$D$"CLOSE"FI$M$D$"DELETE"FI$
+220 PRINT D$"OPEN"FI$M$D$"WRITE"FI$
+230 PRINT "CALL-998:CALL-958:R="E$":CONT"
+240 PRINT D$"CLOSE"FI$M$D$"EXEC"FI$:CALL-998:END:RETURN

Task/Function-composition/Objective-C/function-composition.m

@@ -0,0 +1,42 @@
+#include <Foundation/Foundation.h>
+
+typedef id (^Function)(id);
+
+// a commodity for "encapsulating" double f(double)
+typedef double (*func_t)(double);
+Function encapsulate(func_t f) {
+  return ^(id x) { return @(f([x doubleValue])); };
+}
+
+Function compose(Function a, Function b) {
+  return ^(id x) { return a(b(x)); };
+}
+
+// functions outside...
+double my_f(double x)
+{
+  return x+1.0;
+}
+
+double my_g(double x)
+{
+  return x*x;
+}
+
+
+int main()
+{
+  @autoreleasepool {
+
+    Function f = encapsulate(my_f);
+    Function g = encapsulate(my_g);
+
+    Function composed = compose(f, g);
+
+    printf("g(2.0) = %lf\n", [g(@2.0) doubleValue]);
+    printf("f(2.0) = %lf\n", [f(@2.0) doubleValue]);
+    printf("f(g(2.0)) = %lf\n", [composed(@2.0) doubleValue]);
+
+  }
+  return 0;
+}

Task/Function-composition/Perl-6/function-composition-1.pl6

@@ -1,3 +1,3 @@
 sub infix:<∘> (&f, &g --> Block) {
-    -> $args { f g |$args }
+    -> |args { f g |args }
 }