docs(templating): document the move from slim-sprig to sprout

Add a migration section listing the renamed functions, the ten argument
order changes and the behaviour differences, extend the template function
deprecation page with the new aliases, and point the sprig links at the
sprout documentation.

CHANGELOG.md

@@ -36,6 +36,14 @@
 - Fixed the JSON schema rejecting more keys the Taskfile parser accepts:
   `ignore_error` on a `task:` call, and `if`, `set` and `shopt` on a command
   inside a `for` loop (#2967 by @vmaerten).
+- Migrated the templating engine from `slim-sprig` to
+  [sprout](https://docs.atom.codes/sprout). Every function name Task exposed
+  still resolves, and the ten functions whose argument order changed accept both
+  the old and the new form, reporting the old one under `--verbose`. Some
+  long-standing sprig bugs are fixed as a result, and functions that used to
+  swallow errors now report them — see
+  [Migrating from slim-sprig](https://taskfile.dev/docs/reference/templating#migrating-from-slim-sprig)
+  (#1638, #2006 by @42atomys, by @vmaerten).
 
 ## v3.52.0 - 2026-07-02
 

website/src/docs/deprecations/template-functions.md

@@ -25,3 +25,37 @@ listed besides the function being removed.
 | `FromSlash`         | `fromSlash` |
 | `ToSlash`           | `toSlash`   |
 | `ExeExt`            | `exeExt`    |
+
+## Functions renamed by sprout
+
+Task's generic template functions moved from slim-sprig to
+[sprout](https://docs.atom.codes/sprout), which renamed a number of them. The
+old names still work as aliases, and Task reports their use when run with
+`--verbose`.
+
+| Deprecated function               | Replaced by                      |
+| --------------------------------- | -------------------------------- |
+| `upper`                           | `toUpper`                        |
+| `lower`                           | `toLower`                        |
+| `title`                           | `toTitleCase`                    |
+| `atoi`, `int`                     | `toInt`                          |
+| `int64`                           | `toInt64`                        |
+| `float64`                         | `toFloat64`                      |
+| `toDecimal`                       | `toOctal`                        |
+| `toStrings`                       | `strSlice`                       |
+| `b64enc`, `b64dec`                | `base64Encode`, `base64Decode`   |
+| `b32enc`, `b32dec`                | `base32Encode`, `base32Decode`   |
+| `base`, `dir`, `ext`              | `pathBase`, `pathDir`, `pathExt` |
+| `clean`, `isAbs`                  | `pathClean`, `pathIsAbs`         |
+| `expandenv`                       | `expandEnv`                      |
+| `ago`                             | `dateAgo`                        |
+| `trimall`                         | `trimAll`                        |
+| `push`, `mustPush`                | `append`                         |
+| `tuple`                           | `list`                           |
+| `biggest`                         | `max`                            |
+| `date_in_zone`                    | `dateInZone`                     |
+| `date_modify`, `must_date_modify` | `dateModify`                     |
+
+Ten functions also changed argument order, and the old order is deprecated. See
+[Migrating from slim-sprig](../reference/templating.md#migrating-from-slim-sprig)
+for the full list and for the behaviour changes that came with the move.

website/src/docs/guide.md

@@ -486,7 +486,7 @@ includes:
 Vars declared in the included Taskfile have preference over the variables in the
 including Taskfile! If you want a variable in an included Taskfile to be
 overridable, use the
-[default function](https://sprig.taskfile.dev/defaults.html):
+[default function](https://docs.atom.codes/sprout/registries/std#default):
 <span v-pre>`MY_VAR: '{{.MY_VAR | default "my-default-value"}}'`</span>.
 
 :::

website/src/docs/reference/templating.md

@@ -12,7 +12,7 @@ Task's templating engine uses Go's
 [text/template](https://pkg.go.dev/text/template) package to interpolate values.
 This reference covers the main features and all available functions for creating
 dynamic Taskfiles. Most of the provided functions come from the
-[slim-sprig](https://sprig.taskfile.dev/) library.
+[sprout](https://docs.atom.codes/sprout) library.
 
 ## Basic Usage
 
@@ -444,7 +444,7 @@ tasks:
     vars:
       ITEMS: [a, b, c, d, e]
     cmds:
-      - echo "{{slice .ITEMS 1 3}}"     # [b c]
+      - echo "{{.ITEMS | slice 1 3}}"     # [b c]
 ```
 
 ### String Functions
@@ -540,8 +540,8 @@ tasks:
     cmds:
       - echo "{{.NUMBERS | uniq}}"                       # [3, 1, 4, 5, 9]
       - echo "{{.NUMBERS | sortAlpha}}"                  # [1, 1, 1, 3, 4, 5, 9]
-      - echo"'{{append .FRUITS "cherry"}}""              # ["apple", "banana", "cherry"]
-      - echo "{{ without .NUMBERS 1}}"                   # [3, 4, 5, 9]
+      - echo "{{.FRUITS | append "cherry"}}"             # ["apple", "banana", "cherry"]
+      - echo "{{.NUMBERS | without 1}}"                  # [3, 4, 5, 9]
       - echo "{{.NUMBERS | has 5}}"                      # true
 ```
 
@@ -704,11 +704,10 @@ tasks:
           port: 5432
           ssl: true
     cmds:
-      - echo "Database {{get .CONFIG "database"}}"
-      - echo "Database {{"database" | get .CONFIG}}"
+      - echo "Database {{.CONFIG | get "database"}}"
       - echo "Keys {{.CONFIG | keys}}"
       - echo "Keys {{keys .CONFIG }}"
-      - echo "Has SSL {{hasKey .CONFIG "ssl"}}"
+      - echo "Has SSL {{.CONFIG | hasKey "ssl"}}"
       - echo "{{dict "env" "prod" "debug" false}}"
 ```
 
@@ -858,3 +857,82 @@ tasks:
       - echo '{{printf "Version %s.%d" .VERSION .BUILD}}'
       - echo '{{println "With newline"}}'
 ```
+
+## Migrating from slim-sprig
+
+Task's template functions used to come from
+[slim-sprig](https://sprig.taskfile.dev/), a fork of the unmaintained
+[sprig](https://masterminds.github.io/sprig/) library. They now come from
+[sprout](https://docs.atom.codes/sprout), its maintained successor.
+
+Every function name that slim-sprig provided still resolves, so existing
+Taskfiles keep working. Run Task with `--verbose` to see which of your templates
+rely on a deprecated name or argument order.
+
+### Renamed functions
+
+The old names are kept as deprecated aliases. Prefer the new ones.
+
+| Old name                     | New name                        |
+| ---------------------------- | ------------------------------- |
+| `upper`                      | `toUpper`                       |
+| `lower`                      | `toLower`                       |
+| `title`                      | `toTitleCase`                   |
+| `atoi`, `int`                | `toInt`                         |
+| `int64`                      | `toInt64`                       |
+| `float64`                    | `toFloat64`                     |
+| `toDecimal`                  | `toOctal`                       |
+| `toStrings`                  | `strSlice`                      |
+| `b64enc`, `b64dec`           | `base64Encode`, `base64Decode`  |
+| `b32enc`, `b32dec`           | `base32Encode`, `base32Decode`  |
+| `base`, `dir`, `ext`         | `pathBase`, `pathDir`, `pathExt` |
+| `clean`, `isAbs`             | `pathClean`, `pathIsAbs`        |
+| `expandenv`                  | `expandEnv`                     |
+| `ago`                        | `dateAgo`                       |
+| `trimall`                    | `trimAll`                       |
+| `push`, `mustPush`           | `append`                        |
+| `tuple`                      | `list`                          |
+| `biggest`                    | `max`                           |
+| `date_in_zone`               | `dateInZone`                    |
+| `date_modify`, `must_date_modify` | `dateModify`               |
+
+### Changed argument order
+
+Ten functions now take the map or list they operate on as their **last**
+argument, so that they can be piped into. Task accepts both orders, warning
+about the old one under `--verbose`, but the old order will eventually be
+removed.
+
+| Function                       | Old                          | New                              |
+| ------------------------------ | ---------------------------- | -------------------------------- |
+| `get`, `hasKey`, `unset`       | `{{ get $dict "key" }}`      | `{{ $dict \| get "key" }}`       |
+| `set`                          | `{{ set $dict "k" "v" }}`    | `{{ $dict \| set "k" "v" }}`     |
+| `pick`, `omit`                 | `{{ pick $dict "key" }}`     | `{{ $dict \| pick "key" }}`      |
+| `append`, `prepend`            | `{{ append $list "v" }}`     | `{{ $list \| append "v" }}`      |
+| `without`                      | `{{ without $list "v" }}`    | `{{ $list \| without "v" }}`     |
+| `slice`                        | `{{ slice $list 1 3 }}`      | `{{ $list \| slice 1 3 }}`       |
+
+`dig`, `has`, `chunk` and `merge` kept their argument order.
+
+### Behaviour changes
+
+These are corrections of long-standing sprig bugs, and they are not opt-in.
+
+- Functions that used to swallow an error or panic now report it, failing the
+  task instead of rendering an empty string. `{{ atoi "abc" }}` and
+  `{{ fromJson "not json" }}` are the common cases; their `must` variants
+  behaved this way already.
+- `substr` handles negative indices correctly: `{{ substr 0 -3 "foobar" }}` now
+  yields `foo` rather than `foobar`.
+- `title` applies Unicode title casing: `{{ title "hello wORLD" }}` now yields
+  `Hello World` rather than `Hello WORLD`.
+- `duration` accepts a number of seconds: `{{ duration 90 }}` now yields `1m30s`
+  rather than `0s`.
+- `dig` splits its keys on dots, so `{{ dig "a.b" "fallback" $dict }}` walks
+  into `a` then `b` rather than looking for a literal `a.b` key.
+- `date` and `toDate` interpret a timestamp in UTC rather than in the machine's
+  local timezone. Use `dateInZone` to be explicit.
+
+`merge`, `fromYaml`, `toYaml`, `mustFromYaml` and `mustToYaml` are Task's own
+implementations and are unaffected, even though sprout ships functions of the
+same name.