Idiom

Composite Recipes

Recipes that include further recipes, often including the individual recipes below.

• Apply Kotlin null-safety and scope-function idioms
• Find cast and nullable-shape idioms
• Find collection null-safety idioms
• Find let \{ \} ergonomics
• Find manual null-check idioms
• Find null-assertion polish opportunities
• Find scope-function correctness swaps

Recipes

• Find !! non-null assertions
• Find !! passed as a function argument
• Find ?.apply \{ \} whose result is discarded
• Find ?.let \{ it \} no-ops
• Find ?.let \{ it.foo() \} that could use ?.foo()
• Find ?.let \{ \} calls at statement position
• Find also \{ \} blocks that mutate the receiver
• Find apply \{ \} blocks that perform no mutation
• Find checkNotNull(x) without an explanatory message
• Find filter \{ it != null \}.map \{ it!! \} chains
• Find firstOrNull \{ \} ?: error(...) patterns
• Find if (cond) value else null patterns
• Find if (x != null) x.foo() that could use ?.
• Find if (x != null) y = x.foo() patterns
• Find if (x == null) return ... early-exit patterns
• Find if (x == null) throw ... patterns
• Find listOf(a, b, c).filterNotNull() patterns
• Find long ?. safe-call chains
• Find map \{ ... \}.filterNotNull() chains
• Find nested let \{ \} chains
• Find obj.let \{ fn(it) \} where obj is non-null
• Find redundant this. inside apply \{ \} blocks
• Find requireNotNull(x) without an explanatory message
• Find return null in functions with nullable returns
• Find setOf(a, b, c).filterNotNull() patterns
• Find takeUnless \{ !p \} (double-negative) patterns
• Find unsafe as casts
• Find with(x) \{ ... \} used as an expression
• Find x ?: throw SomeException() without a message
• Find x.run \{ ... \} that doesn't use the receiver
• Find x.takeIf \{ p \}?.let \{ ... \} patterns
• Find x?.firstOrNull() calls
• Find x?.let \{ \} ?: y patterns
• Find x?.something.orEmpty() patterns