feat: add jp functions docs

Signed-off-by: Charles-Edouard Brétéché <charles.edouard@nirmata.com>

pkg/jp/functions/at.go

@@ -7,9 +7,9 @@ import (
 func jpfAt(arguments []any) (any, error) {
 	if slice, ok := arguments[0].([]any); !ok {
 		return nil, errors.New("invalid type, first argument must be an array")
-	} else if index, ok := arguments[1].(int); !ok {
+	} else if index, ok := arguments[1].(float64); !ok {
 		return nil, errors.New("invalid type, second argument must be an int")
 	} else {
-		return slice[index], nil
+		return slice[int(index)], nil
 	}
 }

pkg/jp/functions/functions.go

@@ -9,29 +9,32 @@ func GetFunctions() []functions.FunctionEntry {
 		Name: "at",
 		Arguments: []functions.ArgSpec{
 			{Types: []functions.JpType{functions.JpArray}},
-			// TODO: we should introduce a JpInteger type
-			{Types: []functions.JpType{functions.JpAny}},
+			{Types: []functions.JpType{functions.JpNumber}},
 		},
-		Handler: jpfAt,
+		Handler:     jpfAt,
+		Description: "Returns the element in an array at the given index.",
 	}, {
 		Name: "concat",
 		Arguments: []functions.ArgSpec{
 			{Types: []functions.JpType{functions.JpString}},
 			{Types: []functions.JpType{functions.JpString}},
 		},
-		Handler: jpfConcat,
+		Handler:     jpfConcat,
+		Description: "Concatenates two strings together and returns the result.",
 	}, {
 		Name: "json_parse",
 		Arguments: []functions.ArgSpec{
 			{Types: []functions.JpType{functions.JpString}},
 		},
-		Handler: jpfJsonParse,
+		Handler:     jpfJsonParse,
+		Description: "Parses a given JSON string into an object.",
 	}, {
 		Name: "wildcard",
 		Arguments: []functions.ArgSpec{
 			{Types: []functions.JpType{functions.JpString}},
 			{Types: []functions.JpType{functions.JpString}},
 		},
-		Handler: jpfWildcard,
+		Handler:     jpfWildcard,
+		Description: "Compares a wildcard pattern with a given string and returns if they match or not.",
 	}}
 }