Provide more detail in example

1 files changed, 106 insertions, 0 deletions

diff --git a/readme.md b/readme.md
index defecf3..eb3f631 100644
--- a/readme.md
+++ b/readme.md
@@ -9,6 +9,12 @@ Generic functional programming in C with support for statically allocated memory
 To get started, pack your `Functional` struct with the required pointers and callbacks:
 
 ```C
+Person people[] = {{.age = 19, .name = "Alex"},
+                     {.age = 42, .name = "Jenna"},
+                     {.age = 55, .name = "Tom"}};
+int ages[3];
+Person filteredPeople[3];
+
 Functional f = {
     .args = {.i = 0,
              .n = 3,
@@ -56,3 +62,103 @@ When filtering, `args.i` increments to cover all of `args.arr`, but `arr.storage
 #### f.args.ctxp
 
 Context pointer that is freely available for user use.
+
+### Example
+
+```C
+#include "functional.h"
+#define MAX_STR_SIZE 400
+
+typedef struct {
+  unsigned int age;
+  char* name;
+} Person;
+
+bool shouldIncludePerson(FunctionalArgs* args) {
+  const char* toExclude = args->ctxp;
+  Person* first = args->arr;
+  Person* p = &first[args->i];
+  return p->age > 30 && strcmp(toExclude, p->name);
+}
+
+void* derefPerson(int i, void* arr) {
+  Person* p = arr;
+  return (void*)&p[i];
+}
+
+int stringifyPerson(Person* p, char* out, size_t n) {
+  return snprintf(out, n, "Person %s is %d years of age, yo\n", p->name,
+                  p->age);
+}
+
+void printPerson(Person* p) {
+  char personStr[MAX_STR_SIZE];
+  stringifyPerson(p, personStr, MAX_STR_SIZE);
+  printf("%s", personStr);
+}
+
+void shiftPersonLeft(FunctionalArgs* args) {
+  Person* people = args->arr;
+  for (int i = args->i; i < args->n - 1; i++) {
+    people[i] = people[i + 1];
+  }
+  args->n--;
+}
+
+void mapPersonToAge(FunctionalArgs* args) {
+  int* storage = args->storage;
+  Person* people = args->arr;
+  storage[args->i] = people[args->i].age;
+}
+
+void copyPerson(FunctionalArgs* args) {
+  Person* src = args->arr;
+  Person* dest = args->storage;
+  dest[args->i - args->offset] = src[args->i];
+}
+
+void mapExample(Functional* f) {
+  func_map(f);
+  for (int i = 0; i < f->args.n; i++) {
+    int* ages = f->args.storage;
+    printf("age[%d] = %d\n", i, ages[i]);
+  }
+}
+
+void filterExample(Functional* f) {
+  func_filter(f);
+  for (int i = 0; i < f->args.n; i++) {
+    Person* people = f->args.storage;
+    printPerson(&people[i]);
+  }
+}
+
+void findExample(Functional* f) {
+  Person* olderAndNotHarry = func_find(f);
+  printPerson(olderAndNotHarry);
+}
+
+int main() {
+  Person people[] = {{.age = 19, .name = "Alex"},
+                     {.age = 42, .name = "Jenna"},
+                     {.age = 55, .name = "Tom"}};
+  int ages[3];
+  Person filteredPeople[3];
+  Functional func = {
+      .args = {.i = 0,
+               .n = 3,
+               .arr = (void*)people,
+               .ctxp = (void*)"Harry",
+               .storage = filteredPeople},
+      .filter = shouldIncludePerson,
+      .map = copyPerson,
+      .derefInput = derefPerson,
+  };
+  findExample(&func);
+  filterExample(&func);
+  func.args.storage = ages;
+  func.map = mapPersonToAge;
+  func.args.n = 3;
+  mapExample(&func);
+}
+```